THE GREENSAND AND ITS ORIGIN.

but whether it was mechanical abrasion or chemical solution that removed the foraminiferal shells, whose internal casts formed the greensand deposit of the Cretaceous epoch, must remain for the present an open question."-Dr. Carpenter "On the Nature of the Sea-bottom procured by H.M.S. Challenger." (Ann. and Mag. of Nat. Hist., vol. xv., No. 88, April, 1875.)

THE

HE author of the paper from which the above is extracted proceeds on an assumption which I have met with repeatedly, and which is based on an oft-quoted statement made by the venerable Ehrenberg in 1853, to the effect that the grains of Greensand are for the most part, if not entirely, internal casts of Foraminifera in mineral glauconite. Dr. Carpenter has no hesitation in accepting this statement as proved, and, as shown above, with no qualification whatever, nor, as far as appears, with any attempt at verification; thus giving the weight of his name to the assumption that Greensand is a rock made up of casts of Foraminifera. Now as it is not a fact that greensands of the Cretaceous epoch are always composed of foraminiferal casts, it is time that the statement of Ehrenberg, indorsed so unreservedly by Carpenter, should be challenged. Living in a district where the Greensand is well developed, I long since unsuccessfully attempted to discover the internal casts of which I was told it was composed. As far as Ireland is concerned this is not so. Foraminifera to the number of over 100 species abound in the overlying chalk, the specimens being most beautiful and perfect; but only one species recorded from the Greensand, which, however, is not a cast, but a calcareous shell. This itself is almost conclusive against the assumption that the glauconite grains are casts, as we can hardly suppose that amongst millions of shells none would escape de struction. Further, shells of Foraminifera do occur in the Cambridge Greensand, not mere casts, but perfect calcareous tests, having all the characteristic surface-ornamenation, and without any infilling of glauconite. The occurrence of these shells in the English Greensand does away with the notion that there was something in the waters of the Greensand seas that was destructive of calcareous shells.

chalk rocks of Antrim, Down, and Derry, in the course of three years over which his examinations have extended, more than 120 species of Foraminifera and Ostracoda, in addition to sponge spicula and Bryozoa,* being about one-half the number examined by Ehrenberg himself from cretaceous rocks during a long series of years. Mr. Wright was equally unsuccessful as myself; the rounded angular grains are in most cases too large, and present no real resemblances to the many well-marked forms of Foraminifera.

The assumption that the Greensand is formed of casts of Foraminifera should be rejected for the following reasons:

1st. Foraminiferal shells do occur plentifully and uninjured in the English Greensand; ergo there is no cause for assuming the wholesale destruction of calcareous shells in that epoch.

2nd. Calcareous tests of mollusca have remained; casts are rare in the Greensand.

3rd, and conclusive. The grains of glauconite in the Irish Greensand, when examined under the microscope, show no real resemblance to Foraminifera.

Whilst, for what seem good and sufficient reasons, coming to the conclusion above stated, I do not mean to assert that Ehrenberg stated anything but what was correct as regards the material he examined. Doubtless what he saw seemed to bear out his assertion; but hasty generalizations are the greatest fault of our times, and it is to be deprecated that erroneous statements should go forth under the sanction of high authorities in the scientific world. When one finds that Dr. Carpenter makes a false assumption in a matter that comes under our own observation, it is hard to avoid thinking that he may be equally in error regarding such a hazy question as Eozoon versus the mineral ophite. If any reader of SCIENCE-GOSSIP wishes to examine the subject for himself, I will be happy to send him some of our Greensand for that purpose. Belfast. S. A. STEWART.

ABNORMAL FORM OF MALE FLOWER OF VEGETABLE MARROW.

us molluscan fossils in abundance, and that not in the condition of casts, but having their calcareous tests preserved, and showing the finest striæ uncorroded. I have already stated that I was unable to find any foraminiferal casts in our Greensand, but, as my less-practised eye might err, I requested my friend, Mr. Joseph Wright, F.G.S., to examine the material with the microscope, which he kindly consented to do, portions of the Irish Greensand, and also Greensand from Cambridge, passing under his scrutiny. I have every confidence in Mr. Wright's judgment and acuteness, he having detected in the

lopment of the sexual organs of plants into floral leaves is well known, but the following case of a plant apparently so little prone to mutation as the Vegetable Marrow may not be without interest. The male flower of this plant consists of a monosepalous calyx with five clefts, and contains a single stamen, at the base of which are usually three openings into the nectary, over which the filament

forms a sort of vault.

* Vide "Annual Report and Proceedings of the Belfast Naturalists' Field Club, 1873-74."

two hairs from the interior of the calyx are shown in the bottom of the field of view, for comparison.

The calyx having been carefully removed, the third growth (b, fig. 149) was found to be adherent to the stamen, as shown in fig. 153; its shape was that of a pointed reniform leaf, the petiole being applied to the filament, and the line of junction easily seen; but no such line of demarcation could be distinguished between the anther and the leaf, the structure of the one merging insensibly into that of the other. This leaf was also reflected on itself at various points, and was of a much deeper colour than any other part of the flower, in fact, it was of quite an orange-colour.

Fig. 153.

It is also noticeable that while the anther bore plenty of pollen, the nectary at the base of the filament was totally obliterated, so that the usual inducement for insects to effect fertilization was not offered. There were no indications of any abnormal growths at the other two sutures of the flower. RICHARD C. BAIGENT.

SPAWN OF FROGS AND TOADS.

YOUR correspondent G. M. Doe, in SCIENCE

YOUR

GOSSIP for September, 1875, asks what is the difference between the spawn of frogs and toads, and whether eggs arranged in single strings are toad's spawn?

Some years ago I reared both frogs and toads from the egg to the perfect animal, and on referring to drawings taken at the time, find that toad's spawn is figured in strings, and frog's in lumps. I remember seeing large masses of the latter lying in a shallow pond near Bristol on March 1st, 1862, and plunging my hand into the bitter cold water, found it difficult to drag out a small enough quantity to put into the narrow neck of a picklebottle provided for the purpose, because, as I tried to grasp at the smooth transparent conglomeration of clear eggs, with little black spots in the middle of each, like currants in jelly, the slippery

mass quietly evaded my hold, slid heavily back into the water, and stirred up the mud. So firmly were these apparently impalpable clusters of spawn (say from 4 to 12 inches in diameter) glued as it were to themselves and to each other by the gelatinous covering that surrounds each embryo, that the lumps seem heavier to the touch than to sight.

With toad's spawn it is different; this has to be more carefully looked for, being much smaller, and very likely, as your correspondent says, "in single strings." My drawing gives a string of spawn containing a double row of eggs. It is 2 inches long, lying over the stem of a piece of hornwort, and was found in a deeper pond near Bridport. Each white egg is only about the eighth of an inch in diameter; the black spots in the middle are smaller and darker than the frog's, as also are the tadpoles. Toads' eggs are sometimes half an inch in diameter. Unfortunately I have not kept dates of the different stages of development (as I now should, and would recommend all observers to do the same), and therefore do not know how long a time transpires, after the egg is laid, until the young tadpole is hatched. Probably this and all stages of development depend greatly upon light and temperature. Once I kept a tadpole a whole year before it turned into a frog. The spawn is usually to be found in March.

In England we have two toads and one frog,-the common frog (Rana temporaria), the common toad (Bufo vulgaris), and the aristocratic toad or natterjack (B. calamita). I have reared only common toads and frogs. Nothing is more interesting than to watch the metamorphoses during the larval state. In both species the young can be watched through the transparent egg, which is very small when laid, but afterwards swells, and is largely composed of water. The speck of a tadpole in the centre gradually enlarges into a round black ball; soon the tail uncurls, the head eats its way through the gelatinous covering, and the tadpole is free, appearing with a fringe or tuft of external gills on either side of the head, and remaining generally on or near the eggs until these are eaten up. In a few days they seek other food, the external gills disappear, the animal breathes by internal gills or branchia adapted for breathing air dissolved in water, and swims actively through the water by means of a fish-like tail: at the base of this a pair of legs are eventually seen budding. When these are fully developed, the front limbs spring from behind the head, the tail becomes gradually absorbed, the animal breathes by lungs, and hops out of the water a perfect frog or toad, as the case might be, breathing atmospheric air. The tails do not really drop off, according to popular belief: if they do, why has no man ever seen them? It would be waste of material; in nature nothing is wasted. The tadpoles' tails are absorbed, not lost. I have watched them gradually growing shorter, and have

a drawing showing this stage; but I doubt if any one ever saw them drop off or cast their tails. Yet so widespread is this popular delusion, that even at the late Microscopical Soirée of the British Association at Bristol, learned members, showing the circulation in frogs' feet and tadpoles' gills and tails, were patiently propagating the favourite fact. When asked to prove it, the answer was, "Every one knows it." When asked, had any one ever seen the tails drop off? the only answer was a surprised look of incredulity, as if the interrogator had gone mad. How this odd superstition arose and became so widely disseminated by word of mouth and in print, is hard to say.

This instance again shows how little we know even of our commonest aquatic animals, and how much remains to be learnt. Aquarium science, yet in its infancy, will add important links to our know. ledge, especially in the study of embryology. But in the case of toads and frogs, a large public aquarium, with constant circulation of water, is not necessary. Any one with a little common sense and patience can keep tadpoles. It would be extremely interesting to get a careful set of observations, with locality, names, dates, and drawings of the comparative development from embryo to adult of the common frog (Rana temporaria), the two toads (Bufo vulgaris and B. calamita), and also our water salamanders, tritons, lizards, or newts (Triton aquaticus and T. cristatus). I should be glad to know who is considered the best authority on this subject, and if a series of correct drawings exist. Also I want to know if toad tadpoles ever possess external gills? My drawings do not represent any; in other respects they resemble the frogs: both tadpoles live from about March to August. I have never hatched-out water-lizard tadpoles, but have drawings of four taken Sept. 20, 1860, representing them of different sizes and stages, from half an inch long, with four legs and external gills, to 14 inch, with four legs, a tail, and no external gills; that is, exactly like the adult, but not fully grown. I saw a specimen as large as this, showing the beautiful circulation of the blood through the external gills, last month, at the British Association soirée, Aug. 26. Thus, it appears, as if these young water-lizards are of different ages, and therefore the eggs must be laid at different times. Is this so? J. G. Wood says that the water-lizards (Triton) lay their eggs separately; each single egg is deposited on some water-plant, and that then the leaf is cleverly twisted up so as to protect and conceal it. H. A. Nicholson, in his "Manual of Zoology," distinguishes between the order Urodela, or tailed amphibians, such as water salamanders or tritons, and the Anoura, or tail-less amphibians, as frogs and toads, by saying that "the development of the newts is like that of the frogs, with two points of difference. 1st, that the embryonic tail is not cast

off in the adult; and 2nd, that the fore limbs are developed sooner than the hind limbs, the reverse being the case in the Anoura." The water salamanders, or newts, are furnished with a compressed fish-like tail, and are strictly oviparous (that is, the young are hatched from eggs). The larvæ are tadpole-like in form, with external branchiæ, which they retain till about the third month. The adult is destitute of gills, and breathes by lungs alone, but the larval tail is retained throughout the life of the animal. The land salamanders form the genus Salamandra, and are distinguished from their aquatic brethren by having a cylindrical instead of a compressed tail, and by bringing forth their young alive, or by being ovo-viparous. The water newts and all the Urodela are often completely lizard-like in form when adult, but they always possess gills in the earlier stages of their existence, and this distinguishes them from all the true lizards (Lacertilia). These are related to the giant extinct Saurians.

Thus we have in the frog an animal furnished with three sets of breathing apparatus, four legs, and a tail at different stages of its existence. 1st, external gills as a tadpole; 2nd, internal gills like a fish; 3rd, lurgs adapted for breathing air. The gills and tail, no longer needed for aquatic existence, are absorbed, not lost; the animal steps out of the water a true lung-breathing vertebrate. Next come the Tritons, with external gills for three months instead of three days; lungs appear, and the four legs and tail are retained throughout life. The animal is amphibious, living mostly in the water, but dies for want of breath if kept there, and prevented from coming to the surface to breathe. Next below comes a curious animal, the American Axolotl (Siredon pisciformis), shining like a huge black tadpole 12 or 14 inches long, with four legs, a tail, and a set of external gills, which are retained throughout the whole of its existence. For some time it was supposed to be merely the tadpole, or larval form of some terrestrial animal, but I believe it is never known to leave the water voluntarily, and breeds freely in this condition, laying quantities of eggs, which are easily reared. Strange to say, although it never breathes by anything but gills, it has rudimentary lungs. This tendency to variation, and shadowing forth of higher forms, side by side with persistent types, is intensely interesting, as forming links in Darwin's endless chain of evolution. G. S.

several years my brother has taken large numbers of this butterfly, by far the greater portion having the wings more or less clipped. This was not owing to the length of time they had been out, as the colours were quite fresh and bright. The showier Atalanta is rarely found in this damaged condition. With Hyperanthus the case is different; this insect does not get torn, but soon becomes faded. Cassiope and Medea are still more delicate. And amongst moths, Epunda lutulenta almost directly after emergence adorns itself with notches in its wings, so that specimens-and I have taken many are very difficult to obtain in good order. Who, too, cannot speak from experience of the manner in which the handsome Catocalidæ disfigure themselves? Geometers, as a rule, wear well; doubtless owing to their extreme lightness; though there are exceptions, as Scotosia dubitata, &c. The question arises, why this difference as to the "wearing" of various species? As is well known, the wings are formed by a transparent membrane covered with what are termed scales, arranged somewhat like the tiles on a roof; each having a little stalk which fits into a socket in the membrane. It is said that there is no colouring matter in these scales, but that the colours are produced by the interference and decomposition of light. It follows, then, that the faded appearance cannot be due to any destruction or alteration of colouring matter, as that of the chlorophyll in plants, but must be caused entirely by the loss of the scales; that in some species the scales are attached very slightly, and thus being easily removed, the insect soon looks shabby. Amphipiyra pyramidea and the beautiful Xanthia genus are examples of Lepidoptera with the scales but slightly connected. Contrast these with Aprilina and Meticulosa. Whilst the Sallows will scarcely bear a touch without injury, the last-named may be handled even roughly and not receive any appreciable damage.

With those species which, like Sibylla, Iris, and Lutulenta, are so often caught with little pieces out of their wings, it seems to me we must attribute as the cause thereof the peculiar brittleness of the alar membrane itself.

may be classed, as shallow or dish-shaped, and deep or bowl-shaped. Some of the first are large oval dishes, and seem to be pre-Christian, as they have only been found in the interior of the De Danaan tniams or carns. The accompanying cut, taken from a sketch (fig. 154) given me by the late G. V. du Noyers, M.R.I.A., represents the bullân in the large carn at Slieve-na-Caillighe, county Meath. These large bullâns are oval; and similarshaped ones, but much smaller, occur in, or in the vicinity of, some of these older churches of the West; while in South-east Ireland an intermediate type-round shallow bullâns-have been remarked; one occurring at Bannow, county Wex. ford; while at Donaghmore, in the same county, there is a peculiar, probably uniquely carved bullân. It was cut in a small block of micasyte, was twelve inches in diameter and about three inches deep, its interior being sculptured after a six-cornered cross. It is now broken, and a small portion of it gone, but fig. 155 represents what it originally was.

The second, or bowl-shaped bullâns, are typically Irish. They are generally from twelve to sixteen inches in diameter and from six to ten inches deep, the depth being more than half the diameter. A few are much smaller, about the size of a teacup. Usually they are single, but in places two, three, and, in one instance, five have been recorded as occurring together in one block of stone. In general, a very hard stone has been selected by the stone-cutter; thus, in the county Galway they have been scooped out in granite or sandstone erratics. Of those we have seen, only four were in limestone, one of which is a blessed well, hereafter to be mentioned, on Aranmore; two, forming wells, which seem to be modern, occur together at Lisdoonvarna, county Clare; while the fourth was lately pointed out by Mr. Fitzgerald, of Holy Cross, Lough Gur, county Limerick. All these bullâns are cut in the solid rock, but the latter, which lies a little south-east of the historical Lough Gur, is also remarkable for its unique shape, being an inverted cone nineteen inches deep and twelve or thirteen inches in diameter (fig. 156).

This class of bullân in general occurs in the vicinity of churches, but not always. In the valley north of Adrigole, Bantry Bay, a so-called holy well, is a bullân that was cut in the horizontal stone of a cromleac, while on the hill north-west of the same village is a second bullân cut in a block of stone, that seems also to have been a portion of a cromleac; and in the hills north-east of Tulla, county Clare, a bullân cut in the solid rock (sandstone) was observed. None of these places seem to be at all connected with ancient ecclesiastical establishments.

What were the bullâns? It has been suggested that the bullâns in the carns were corn-crushers, such structures having been built not as burial