Basal pieces three, large, nearly equal in size, forming together a basis resembling a thick button, the margins projecting a considerable distance beyond the body where it joins to it, deeply concave below, the depression left by the column forming a still deeper concavity, occupying about half the diameter of the whole base, the centre being perforated by a small pentapetalous opening. First radials five, very minute, quadrangular, thrice as wide as high. Second radials similar in form and size to the first radials. The third radials are axillary, twice the size of the first, and support on each bevilled edge two pentagonal secondary radials, the last of which are again axillary, giving off two rows of three pieces each to the free arms, except in the postero-lateral rays, where the third secondary radial becomes again axillary and supports on each bevilled edge two rows of three pieces which reach to the free arms; the postero-lateral rays supporting five arms each, the others only four. The brachials are considerably broader than long, and so arranged that the salient angle of one piece fits into the retreating angle formed by the two pieces opposite it. Commencing at the junction of the base with the first radials rises a row of single carinated protuberances, more or less prominent, extending from the base along the middle of the rays and their branches to the free arms distinctly marking the course of the rays. Interradials usually two, a large hexagonal one followed by a smaller one of similar form. Anal pieces six, the inferior three are pentagonal, their inferior and lateral margins nearly equal, the lines defining the upper are shorter and produce a sharp angular point at the summit of the pieces; between these angular points of the first range, rest two hexagonal pieces a little inferior in size to the first; upon these last rests a hexagonal piece still less than those of the second range. The surface of the anal and interradial pieces are plain surfaces, except the fine granular markings before described. Vault. The vault is of an elevated conical form surmounted by a proboscis, the whole being covered by irregular sized pieces, generally hexagonal in form, rising from the margins toward the centre and terminating in a point-in some specimens, the centre of the pieces are marked by two or sometimes three points. It happens that all these forms are found in the same specimen. Arms. The arms of this splendid crinoid are so unlike anything before described as to merit special attention. They are (on medium sized specimens), about four inches in length. They rise from the calyx in a sub-rotund column about one third of their length, when they flatten and expand towards the top; at the middle of their length they are half an inch wide and about a sixteenth of an inch thick, for a short distance the margins are parallel when they suddenly contract by a graceful curve to about half their greatest width, the sides again becoming parallel for half an inch, when they close by a circular curve which bounds the upper extremnity. The insides of the lower parts of these arms are flattened and grooved by a deep semicircular sulculus, the margins of which are lined with very fine, long cilia up to the enlargement of the arms, beyond which they cannot be traced, in fact we suppose they extend only so far. The body of the arm is composed of a double row of pieces, very small below, increasing in size upward; where the arms are most expanded they number about twenty-four to the inch, in the lowest part from thirty-six to thirty-eight to the inch. quar Geological position and locality. Found in vast numbers in the ries near the Louisville and Nashville Rail Road, Clear Creek, Hardin Co. Kentucky, at numerous localities in Indiana, in beds near the top of the Knob member of the sub-carboniferous rocks. On Clear Creek the horizon of our species is 180 feet below the equivalent of the Batocrinus and fish beds of Spurgen Hill, Indiana. The arms, and in the absence of these, the general form, especially the button-like projecting base, distinguish this from Actinocrinus. « Dimensions of medium sized specimen. Height from base to foot of proboscis, 1.45 inch. 45 66 1.7 66 Height of base, MEGISTOCRINUS, Owen and Shumard. Megistocrinus rugosus, sp. nobis. Body subglobose, truncated; below the truncation concave: from the second radials to the summit it is subcylindrical, thence assuming an unsymetrical, subconoidal form; surmounted by a long proboscis. The pieces of the calyx being ornamented with very prominent angular tubercles, give it an exceedingly rugose appearance, hence its specific nante. Column round, composed of alternate thicker and thinner pieces, the thinner ones being broader than the others. Articulating surfaces marked by very short striæ confined to the outer margin, canal pentapetalous. Basal pieces, three, forming together an irregular hexagon, the longest diameter of which is parallel to the anal side. The first facet of the column covers nearly four-fifths of the base: outside of this facet, these edges are finely granulated. First radials, five, forming together with the first anal piece a circle of very symmetrical hexagonal pieces. Their surfaces are beautifully ornamented with striæ disposed hexagonally and interspersed with granular markings. Second radials, five, also hexagonal though not so regular in form as the preceding ones. That portion of their surface lying nearest to the first radials is generally ornamented with fine granular markings, whilst the portion joining the third radials is strongly tuberculated, this peculiarity together with the comparatively smooth surfaces of the basal pieces, first and second radials, and the intervening interradials, forms a striking contrast with the rough sides and prominent thorns of the upper surface of our species. This dis Third radials, five, generally irregularly hexagonal, thick, tuberculated, axillary, and support each two brachials. In three of the rays they are axillary, and support on each facet one or two pieces, from which proceed. the free arms, each ray thus supporting four arms. In the two remaining rays they are also axillary and support one or two pieces each, the ray having only one pair of arms, thus making in all sixteen arms. position of the number of arms in a ray is constant and characteristic. Interradials. These vary in adult specimens from thirteen to fifteen, in younger ones we generally find seven or eight. The first three or four pieces of the interradial fields are hexagonal. Situated between the radials, which they resemble in size, form and ornament, the remaining pieces of these fields become gradually smaller, and are less regular in their form and disposition. All of these as well as the other pieces forming the sides of the calyx are very thick, and ornamented by prominent arm bones, or boss-like projections. They are joined together only at their lower edges, the upper portion of each piece being free and separated from the contiguous one by deep sulculi. Anal pieces, fifteen to twenty-five, varying with the age of the specimen; presenting much the same character as the interradials just mentioned. The one resting on the base is equal in size to the first radials which it resembles, this is succeeded by three large hexagonal pieces, nearly in a line with the second radials, the remainder are smaller and irregularly disposed. Interbrachials. Between the brachials, and in a line with the radials, are interbrachial pieces, one large and two smaller pieces. In the second bifurcation, in those rays having four arms, and between the last brachials, there is generally one other interbrachial interposed, sometimes two or three. The arms are sixteen in number running off in two pairs of two, and three sets of four. Vault. The vault is covered by small polygonal pieces arranged in clusters of seven to ten about a central one, which is usually larger than the surrounding pieces, and usually spinigerous. With the exception of the spines, the vault is devoid of ornament. The pieces are raised in the centre giving this part a varicose appearance. The proboscis is long, subcentral, composed of pieces similar to those of the vault; at or near the base of it is a spine which is nearly central, or somewhat larger than any other spine upon the summit. Geological position and locality. This magnificent crinoid is found in considerable numbers in rocks of the Devonian period, a few feet beneath the black slate, at the quarries on Bear grass Creek near Louisville, Ky. We have referred this fossil to the genus megistocrinus, which it resembles so closely in the number and arrangement of the pieces that such disposition of it will hardly be questioned. It is found in the Devonian rocks of the age of the Hamilton group, associated with Orthis suborbicularis, Atrypa reticularis, A. aspera, Euomphalus cyclostomus? &c. This is about the same horizon in which Hall found his Megistocrinus latus. A fossil closely allied to this is found in the Devonian rocks of Spain, and described by De Verneuil as Pradocrinus Baylii,* a second species P. Americanus, is found on the Falls of the Ohio. * Bulletin de la Geol. Soc. de France, 2d Series, t. vii, p. 137, pl. 2, fig. 11. CYATHOCRINUS, Miller. Cyathocrinus multibrachiatus, sp. nobis. Calyx, vasiform, the pieces thick and tumid, surface ornamented with confluent granulose markings. Column, round, proportionally small. Basals, five, pentagonal rather large; their under surfaces are scooped out forming a patelloid excavation which is entirely overspread by the column. Their superior margins are prolonged into angles. Subradials, five, fitting into the retreating angles of the basis, four of them are hexagonal, the fifth, the anal piece, is heptagonal. Of these pieces the two postero-lateral ones are larger than the two antero-lateral one; the anal piece is yet larger and longer than any of the remainder. From the prominent centre of each piece, broad plications, vaguely marked proceed to the margins. First radials, five, generally pentagonal, their width double their height, ornature same as on the other pieces, their upper edges are bevilled, near the centre of each of these edges is a cicatrix bounded by a strong thick margin, which occupies from one-third to one-half of the width of the piece, these support the remaining radial pieces which vary in different rays from two to seven in number, they are very irregular in size though usually wider than high. Anal pieces, two, the first is obscurely heptagonal, larger than any of the other pieces of the calyx, succeeded by a small parallelogramic piece which forms the basis of the proboscis. Vault. The form of the pieces composing the vault is unknown. The proboscis is excentric, occupies about one-third of the whole summit and is composed of small irregular hexagonal pieces whose surfaces are thickly studded with fine granulæ. Its length equals the height of the calyx. Arms. From the last radial pieces of each ray there extend laterally two strong branches, each of which give off five or six smaller ones, these become subdivided and decrease regularly in size as they proceed from the axillary radials: this arrangement can be perceived only when portions of the arms have been removed, as they interlace and overlap each other. The pieces composing the arms have a parallelogramic form, their places of articulation marked by an elevated rim, surfaces otherwise perfectly smooth. We may readily suppose that at their final development the arms number from one hundred to one hundred and twenty. Our specimen resembles Cyathocrinus intermedius of Hall (Iowa, p. 627, pl. 18, fig. 10), yet the differences are so marked that they will be easily distinguished. Position and locality. Found in the subcarboniferous beds of Montgomery Co., Indiana, associated with Forbesiocrinus, Platycrinus, Goniasteroidocrinus and other crinoidal remains similar to those of the Keokuck limestone of Iowa. Cyathocrinus multibrachiatus, var. The basal, subradial, radial and anal pieces have the same form, relative size and position as in C. multibrachiatus. In the specimen figured the surfaces of all the pieces forming the calyx are destitute of any markings, wanting entirely the plications and granular ornature found on the species above referred to; although this is true of another specimen in our collection, we suppose it owing to the imperfect conservation of those particular specimens rather than a constant characteristic of the variety. The principal differences are in the arms and the proboscis. The pieces composing the proboscis of the variety are arranged in parallel rows instead of alternating with each other as they do in C. multibrachiatus. The arms of the variety come off as in the species, namely, the last radial piece which is axillary, supports two rays of arms, but the secondary branches such as noticed in the description of the species continue in most instances throughout their whole length without bifurcations. This arrangement will be easily understood by reference to plate 5,* fig. b, 1, 2. Position and locality. This crinoid occurs in the same beds as its congener described above. ART. XXX.-Contributions to Mineralogy; by FREDK. A. GENTH. 1. Native Iron. ABOUT four years ago I received for examination a mineral, which was said to be found in the neighborhood of Knoxville, Tennessee, in considerable quantities, and which was believed to be a valuable nickel ore. A qualitative analysis of it, made at that time, proved it to be almost pure iron, and the total absence of carbon, phosphorus and sulphur, and its peculiar appearance, made it very probable that it was real native iron. The specimen, which I received was 1x1 in size, on one side of it the iron was th, on the other th of an inch in thickness; on one side it was incrusted by a silicate of iron, magnesia and lime. The iron itself is of a greyish white color, a hackly fracture, and breaks easily into fragments of an irregular shape, which are crystalline, without, however, showing signs of any distinct planes. It is soft and scratches fluorspar with difficulty. Lustre eminently metalic. Dissolves readily in nitric acid. It was found to contain: About a year after I had examined the mineral from Knoxville, I received the same substance from northern Alabama as an alloy of gold, platinum, silver, copper, etc., with the request to advise a plan for the separation of these metals. I have endeavored to obtain more of this interesting substance from both localities, but the parties, probably not being satisfied *To be given hereafter. |