but darker, and the segments of the abdomen below are more narrowly bordered with yellow. Note different from that of C. septendecim, and more like that of some of the grasshoppers. Inhabits the neighborhood of Philadelphia, appearing in the winged or perfect state at intervals of seventeen years.

Note on the above species of CICADA, and on the CICADA SEPTENDECIM, Linn. BY JOHN CASSIN.

There are two distinct and easily recognized species of Cicada which appear at intervals of seventeen years, and both of which were observed in this neighborhood, especially in the woods at Powelton, during the present year. I saw them in Delaware county, Pennsylvania, in 1834, and their entire specific distinctness I have insisted on through good and evil report for the last seventeen years.

It was, therefore, highly gratifying to me to have an opportunity of calling the attention of the gentlemen of this Academy to the smaller species which Professor Fisher has done me the honor of naming as above, and particularly to its note. This is quite different from the prolonged and loud scream of the larger species, (which is C. septendecim, Linn.) and begins with an introductory clip, clip, quite peculiar. No disposition to associate with each other exists between the two species, and although I have seen both on the same tree, yet most frequently they were entirely separated, and occupied different parts of the woods. In 1834, I observed the smaller species in localities which were somewhat favorably situated for moisture, but during the present year it occurred in localities as varied as those of the other and larger species. At Powelton it was very abundant in an orchard of apple trees on the most elevated part of the estate, and also on trees in the adjacent woods.

That the smaller species preferred low grounds was the observation of Dr. Hildreth, of Marietta, Ohio, who, in an article on the Cicada septendecim, in Silliman's Journal, xviii. p. 47, (1830) has the following paragraph:-"There appeared to be two varieties of the Cicada, one smaller than the other; there was also a striking difference in their notes. The smaller variety was more common in the bottom lands and the larger in the hills."

The size and the peculiar note are the most striking characters of the smaller species, otherwise it much resembles the larger. The consideration of its claims to specific distinction involves the general problem of specific character, which is difficult in theory, but practically is readily solved. An animal which constantly perpetuates its kind, or in other words reproduces itself either exactly or within a demonstrable range of variation, is a species. These two Cicada do not associate together as varieties commonly do. Of the very numerous instances in which the phenomenon introductory to propagation has been observed this year, in the course of the particular attention paid to these insects by gentlemen of this Academy, not one case occurred in which the male and female of the two insects were seen together. They are distinct species.

The appearance of the Cicada septendecim in various localities at different periods, each terminating intervals of seventeen years, for instance in Ohio in 1846 and in Eastern Pennsylvania in 1851, is a matter of remarkable interest. Many independent ranges or provinces are known to exist in the United States, and they are now ascertained to be so numerous that this species probably appears

in some part of the country every year. Assuming all that part of North America in which it has ever been observed to be its zoological province, how are the sub-provinces and different times of appearance to be accounted for? Are all those sub-provinces to be regarded as the theatres of independent creations? Do the facts demonstrate that the same species may exist in provinces which may be presumed to have had different eras of origin?

It would be a curious fact, and one of important application, that exactly the same species can inhabit provinces having independent creations, and if, too, as in the case of this insect, it should be clearly impossible for it to have extended from one province to another.

Or, can it be possible that every distinct district in which the Cicade appear is really an entomological province, and that entomological provinces in this part of North America are quite restricted in extent, as has been observed by Dr. LeConte in California? (Communicated by that gentlemen to the American Association for the advancement of Science at its meeting in August, 1851.)

Those sub-provinces may have relations to geologic changes. Having the extraordinary characteristic necessity of remaining in the earth for seventeen years, as a fact in the history of this insect, may it be possible to infer that geologic changes have effected the difference in the times of its appearance, or that so short periods as fractions of seventeen years have been of geologic importance throughout the range of the Cicada?

The Cicada septendecim has appeared in the vicinity of Philadelphia, at intervals of seventeen years, certainly since 1715. There has been, it appears, no variation of temperature, nor causes accidental nor other since that date sufficient to affect its habits in any perceptible degree. It is stated in Clay's Swedish Annals, to have appeared in May, 1715, in this neighborhood, (which, so far as I know, is the earliest authentic record ;) punctually in the same month, every seventeenth year, now certainly for nearly one hundred and fifty years, has this extraordinary insect been known to make its visit. No causes have affected it during that period, not even so far as relates to the month in which it appears.

Passing, I would observe that so far as relates to the neighborhood of Philadelphia, the Cicada septendecim clearly had not a fair start with the year 1,-anno mundi of the commonly received chronology. If it had had, the sum produced by 18514004—1 ought to divide by 17 without a remainder, which it will not do,— more insignificant facts than which have troubled schoolmen.

I have never seen any animals more entirely stupid than the seventeen year Locusts. They make no effort to escape, but allow themselves to be captured with perfect passiveness, thus reminding one of the tameness of animals in countries where they are not molested by enemies. All animals of as high grade of organization as these insects, acquire instincts from impressions made by the presence of danger and otherwise, which they transmit to their offspring. The young Fox of to-day is undoubtedly superior to his juvenile progenitor of a century since. The cicada have acquired no such instinct. Their short life of maturity above the surface of the earth, does not appear to be of sufficient duration for such to be formed and impressed on their posterity.

In short, it appears to me that the study of these insects, and the examination of their separate ranges, might result in conclusions of extraordinary importance, especially relative to modern views of the distribution of animals. No animal is

more easily traced. In other aspects, too, they present interesting points for study, perhaps of general interest in zoological science.

Dr. Zantzinger offered the following, which was adopted, Resolved, That a member of the Society be appointed to prepare a new and extended "Notice cf the Academy," to be read before the Society, and designed for publication.

The Chairman on motion being authorized to make the appointment, selected Dr. Ruschenberger, who accepted the same.

ELECTION.

The Rev. Lorenzo L. Longstreth, of Philadelphia, was elected a Member of the Academy.

October 7th.

Vice President BRIDGES in the Chair.

Dr. Leidy read a paper intended for publication in the Proceedings, entitled "Corrections and Additions to former papers on Helminthology published in the Proceedings of the Academy of Natural Sciences of Philadelphia," which was referred to Dr. Zantzinger, Dr. Fisher, and Dr. Watson.

A letter was read from the Secretary of the Geological Society of London, dated May 1st, 1851, acknowledging the receipt of recent numbers of the Proeeedings.

Dr. Leidy remarked, the members probably recollected that a few evenings since he had mentioned, that it had been asserted by numerous and good authorities, that Gordii had been observed within the body of insects. He now exhibited a specimen of a Gordius and a grasshopper, preserved in a bottle of alcohol, which had been sent to him by his friend Dr. Budd, of Pemberton, New Jersey. The Gordius, Dr. Budd stated, was seen to come out of the body of the grasshopper, and in a half an hour afterwards died. It is a different species from those described a short time since. It is a female, about six inches long, by half a line in length, rigid, strongly marked by transverse wrinkles, and annuli, with the caudal extremity somewhat compressed and obtuse. To the species he gave the name Gordius robustus.

He also exhibited a species of Mermis from Brazil, belonging to the collection of the Academy. It is fourteen and a half inches long, and of a reddish brown color. To it he gave the name Mermis ferruginea.

October 14th.

Vice President BRIDGES in the Chair.

Mr. Cassin read a paper entitled "Catalogue of the Caprimulgidæ in the collection of the Academy of Natural Sciences of Philadelphia,"

which was referred to Dr. Wilson, Col. G. A. McCall, and Dr. Watson.

Mr. Charles Girard read a paper entitled "Historical Sketch of the Gordiacia," which, being intended for publication, was referred to a Committeee consisting of Dr. Leidy, Dr. Hallowell, and Dr. Horner.

Dr. Fisher read a note from Dr. C. D. Meigs, announcing that he was now prepared to read before the Society his biographical Memoir of the late Dr. Morton.

Professor Horner narrated a case illustrating the extreme lethargy produced by the action of Carbonic acid gas on the human system. The individual, while engaged in burning lime, had fallen asleep during the night upon the edge of the kiln, and had been exposed to the action of this gas for many successive hours. A great part of the right fore arm, arm, scapula, and back had been severely burned, without the knowledge of the patient, until he was extricated by persons passing next morning.

Dr. Leidy presented for the inspection of the members a mutilated cranium of an extinct mammal, formerly characterized by him under the name of Oreodon robustum.* It was one of five specimens of crania of the same species lately received through Professor Baird from the Smithsonian Institute. When first obtained, one side was completely enveloped within a matrix, upon the removal of which the complete dentition of the animal was disclosed. The teeth form a continuous arch as in Anoplotherium. The formula is m. 3, p. m. 4, c. 1, i. ¿ upon each side.

Dr. L. also exhibited three inferior molars of the Rhinoceros occidentalis,† of which the posterior measured seventeen lines antero-posteriorly, and ten lines transversely; the others about fourteen lines antero-posteriorly, and ten lines transversely.

Dr. Fisher offered the following, which was adopted.

Resolved, That an invitation be sent by the Secretary, through the Dean of each of the four Medical Colleges, of this city, to the students attending lectures at the respective institutions, to visit the Museum of the Academy on Tuesdays and Fridays, (public days,) and to inform them that they will be admitted upon exhibiting their matriculation tickets.

Mr. Vaux offered the following, which was also adopted.

Resolved, That the Committee appointed at a meeting of the Academy, held May 16th, 1851, to select a Biographer of the late Dr. Morton, be requested to obtain a suitable place for hearing the Memoir by Dr. Meigs, and to make such other arrangements as may be requisite.

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October 21st.

Vice-President BRIDGES in the Chair.

Mr. Lea read a paper on the genus Acostaa of D'Orbigny, a new fresh water mollusc of the order Dimyaria, from the river Guadua, New Granada.

Mr. Lea considers this shell as one of the most remarkable and interesting which has ever come under his notice. The fact that it is in its young state a free bimusculose shell, and in its mature state an affixed unimusculose shell, places it among the anomalies which zoologists find it diffiult to understand, but which, in this case, points out its true position in a natural arrangement. Mr. Lea expressed his convictions that this shell, now so well described by M. D'Orbigny, belonged to the same genus which Ferussac described in 1823, in the Mem. of the Soc. Nat. Hist., Vol. 1, under the name of Mulleria, if it be not of the same species, a single specimen (adult) of which had then only been seen. Ferussac, considering the general resemblance of Mulleria to Ostrea, thought it ought to be put alongside of, if not in, the latter genus. Brongniart and Latreille thought it ought to go between Spondylus and Arca. Other authors had assigned it to various positions, while some doubted whether it was anything more than a malformation. The perfect specimen, in its junior and adult state, if it be Mulleria, now banish all difficulties. Mr. Lea thinks now, in placing Mulleria (Acostæa) in its true position, at the head of the order Monomyaria, where it makes the link with Dimyaria, it forms an easy transition from the first to the second order. Thus retaining the trace of one while it passes so curiously into the other. Nihil per saltum.

Mr. Lea, under the impression that D'Orbigny's Acostaa Guaduasana may prove to be a distinct species from the shell described by Ferussac, under the generic name of Mulleria, while it may belong to the same genus, proposes to give the name of that distinguished zoologist to it. That of Guaduasana should be retained of course for D'Orbigny's species. The genus would then represent Mulleria Ferussacii, and Mulleria Guaduasana.

The paper being intended for publication in the Journal, was referred to Dr. Leidy, Dr. Ruschenberger, and Dr. Wilson.

Dr. Fisher, on behalf of the Committee on the Memoir of Dr. Morton, reported that they had selected the Hall of the University of Pennsylvania, and had appointed the first Thursday in November as the time for hearing the Memoir read by Dr. Meigs, provided the consent of the Trustees of the University could be had, notice of which would be given.

On motion of Dr. Leidy, it was

Resolved, That persons, not members of the Academy, who may contribute to the Museum or Library specimens of Natural History or Books, deemed of sufficient value by the Curators or Librarian, be entitled to a ticket of admission to the Museum on public days, for a period of six months.