from an alternation of contraction and dilatation, corresponding usually to ten segments, into which the animal may subdivide, but more or less disappearing in elongation of the body, becoming more apparent by wrinkling in shortening of the body; anteriorly semi-ovate, sub-acute; posteriorly elongated, cylindroid, obtusely rounded. Apparent segments panduriform, furnished each posteriorly with a clear globular nucleolated nucleus. Intestine variable in capacity, usually dilated in the anterior dilatation of each apparent segment, and much contracted in the intervals. Length from 1-2 to 2 lines, shortening to 1 or 1-4 a line; breadth, when elongated, from 1-400th to 1-300th in.; when shortened from 1-300th in. to 1-2 of a line. Habitation and Remarks.—Found in the same situation as the preceding, creeping planaria-like upon different substances, or most frequently holding a vertical position in the water, apparently without movement, but retaining their position by means of the actively moving vibrillæ, which are comparatively larger than in the preceding worms. They appear to feed upon vegetable particles brought to the mouth by means of the currents produced by vibrillæ. The intestine is usually empty, except at the dilated portions, where it is yellowish or greenish, from granular matters contained within. The whole structure of the animal is exceedingly simple, composed of nucleolated, granular corpuscles, those forming the exterior of the body being furnished with vibrillæ. Under slight pressure, these corpuscles undergo separation from one another, and become globular by endosmosis; in this state they measure from the 1-7000th in. to the 1-2800th in. The nucleoli are globular, shining, and measure the 1-900th in. in diameter. The exterior vibrillated corpuscles, after separation from the body, often move about for some seconds. The vibrillæ measure about 1-3500th in. long. Each segment of the animal's body, at its posterior part, contains a globular, transparent nucleus, measuring the 1-2333d in. in diameter, with a globular, refractile nucleolus the 1-7000th in. in diameter. This latter body, with the form of the apparent segments, makes the animal resemble a row of gregarinæ attached together. The Committee on the following paper by Mr. Cassin, read Dec. 24th, 1850, reported in favor of publication in the Proceedings. Notice of an American species of Duck, hitherto regarded as identical with the Oidemia fusca, (Linn.) BY JOHN CASSIN. Oidemia velvetina, nobis. Audubon, Birds of Am. pl. 247. Form. Generally similar to that of O. fusca, but is rather larger, bill longer and more slender, with the protuberance at the base of the upper mandible more prominent and more extended. Space between the nostril and the edge of the upper mandible much narrower in the present species. Upon the protuberance at the base of the bill in this species, the velvet like plumage of the front terminates in a well defined point, as represented in the figure of the female in Aud. pl. 247, while in O. fusca this termination is abruptly sub-rounded as in both figures in Selby, Ill. pl. 67, though I have never seen a specimen in which this rounded character is so distinctly marked as there represented. Color.Entirely black, except a spot under the eye and the exposed portion of the secondaries, which are white. The white spot under the eye is larger in the species now described. Hab.-Atlantic coast of North America. Obs. The two species here alluded to are easily distinguished from each other when examined together, and both may possibly be found in America and Europe. The pointed extension of the velvety plumage upon the upper mandible is the most ready character by which the species now described may be known. It appears to be the bird figured by both Wilson and Audubon as the Anas fusca, Linn. Specimens of both species are in the collection of this Society; the specimen which led to their examination was shot at Egg Harbor. N. J., and presented recently by our fellow member, E. J. Lewis, M. D. The annual Report of the Treasurer was read and referred to the Auditors. The Report of the Librarian was read, as follows: The additions to the Library, of all descriptions, during the present year amount to 2965, this number being more than double that of 1849, and far exceeding the ratio of any previous year since 1834. The subjoined table has been prepared in the ordinary form, presenting the number of volumes, pamphlets, and works in parts or numbers, in each subject. Of the whole number 2965, there have been contributed by authors 74; by editors 18; by members, correspondents, and others 109; by societies and corporations 113; by Dr. Wilson 2493; by Mr. Edward Wilson, of Wales, 153; by the U. S. Treasury Department 5 (charts.) The extensive contributions of Dr. Wilson to the Library, including those of the present and previous years, are now the property of the Society, on the sole condition that they are not to be loaned from the Hall. The propriety of this restriction is unhesitatingly acknowledged by all connected with the institution. It is also in entire accordance with the views of the earlier members of the Society, among them Mr. Maclure, who was decidedly in favor "of making the Library a Reading Room, with all possible facilities for those persons who wish to consult the books." I quote from the excellent report of the Library committee presented in 1836. These facilities are now certainly all that can be desired, and we may even hope that the restriction will be extended by an act of the Society, to all the books contained in the Library, no exceptions being made as at present. Among the many valuable additions this year, may be mentioned the following:-D'Orbigny's Palæontologie Française, nearly complete, from Dr. Morton; Blainville's Ostéographie as far as published; Demidoff's Voyage dans la Russie Meridionale; Paxton's Magazine of Botany, Vols. 1 to 17: Memoirs of the Royal Society of Lille, 26 vols.; Commentationes Soc. Reg. Sci. Gottingensis, 32 vols.; Comptes Rendus, vols. 1 to 23, (completing the series in the Library ;) Aunales des Sciences Nat., 3d series, 20 vols.; Miscellanea curiosa, Ephemerides, Acta Physico-medica, and Nova Acta Acad. Cæsar, Leopold-Carolina Nat. Curiosorum, about 80 vols.; Commercium Litterarium, 15 vols.; Transactions of several Berlin Societies, 39 vols.; Annales Acad. Rheno-Trajectinæ, 25 vols.; Memoires, Annales, Nouv. Annales, et Archives du Museum d'Hist. Nat. de Paris, 21 vois. (completing the Academy's series ;) Commentarii de Rebus, 44 vols.; Diction naire des Sci. Nat. 75 vols.; Trans. of Royal Irish Academy, vols. 1 to 13; of the Royal Asiatic Society, vols. 1 to 10; Journal of the Royal Geographical Society, vols. 1 to 19; Brewster's Edinburgh Journal of Science, and Brande's do. 32 vols.; Dict. classique d'Hist. nat. 17 vols.; Shaw's General Zoology, 14 vols.; for all of which we are indebted to the untiring liberality of Dr. Wilson. Mr. Edward Wilson, of Pembrokeshire, Wales, the brother of our esteemed fellow-member, has been a large contributor to the Library during the present year. He has also been instrumental in creating an interest in the Library with other friends of our institution abroad, and among them a number of naturalists and men of science, from whom we have already derived numerous highly acceptable contributions. Through exchanges with Societies, we continue to receive considerable accessions to the Journal department. To the "Ecole des Mines," of Paris, we are particularly indebted this year, for eighteen volumes of the Journal and Annales des Mines. Our series of that valuable periodical is now complete, with the exception of three or four volumes. The exchange list, however, is not yet as desirable as we hope it will be, when our relations with foreign scientific bodies are more extended, and placed upon a better and more permanent footing than at present. The extraordinary rapidity with which the Library of our favored institution has advanced of late years, has astonished and gratified all connected with it. In the last annual report it was stated that, in consequence of its great increase, it had become necessary to extend the accommodations for books into the adjoining room, and that arrangements were then being made for that purpose. The alterations were soon afterwards completed, and the apartment has been fitted up in a tasteful and commodious manner. The cases on the floor contain the various Transactions, Journals, and similar works, and those on the gallery are entirely occupied with the Dictionaries of Arts and Sciences, and the valuable collection of works on Antiquities and the Fine Arts. The Library has increased from about 7000 volumes in 1836, to upwards of 12,000 volumes in 1850, a period of about fourteen years, nearly all of which have been the gratuitous contributions of individuals or societies, very few having been obtained by purchase, or through public sources. The annexed statement shows the number of volumes in each department, ascertained by actual enumeration within the last few days. The following report was read by Dr. Leidy, Chairman of the Curators : REPORT OF THE CURATORS For 1850. The museum of the Academy has continued to increase during the year just closing, with the vigor which characterized it the preceding two years. Several of the departments have received very large accessions; others, which from their comparative state of completeness preclude any extensive contributions, have received donations of value and rarity; and all have had important additions. The arrangement of the Cabinet of the Academy devolves upon a few members, who being able to devote but a portion of their time to the purpose, from the extent of the collection it must be necessarily slow. One of our most important aids in this respect we lost last summer: I allude to our much lamented fellow-member and Vice President, Dr. R. E. Griffith, who was steadily engaged, during his moments of leisure, in arranging the conchological collection, to which he had so extensively and liberally contributed. The Academy has also been unfortunate this year in the loss of another of its important members, Dr. Gambel, one of our best and most enterprising ornithologists, who, when at home, frequently lent his valuable assistance in arranging the ornithological collection. All objects of the museum of a destructible character are in a good state of preservation, and appear to be well protected from the attacks of Dermestes and Ptinus by the vapor of ether, which has been lately introduced into use for this purpose by Dr. Wilson. The increase in the cabinet during this year, will be briefly noticed under the head of each respective department. Mammalia. In this class the Academy has been greatly enriched by the addition of the collection of Dr. J. K. Townsend, made by himself in the Rocky Mountains and Oregon, consisting of 37 species, 56 specimens, in skin, in a good state of preservation. These were liberally presented to the Society by Dr. Townsend: Most of them are the specimens from which the species were originally described, and many of them are exceedingly rare in natural history collections, and a few are unique. Among them are two specimens of the gigantic wolf of America, Lupus gigas, lately described by Dr. Townsend in the Journal of the Academy. We have also received skins of twenty species of mammalia,† of Europe, Asia, Africa, and Australia, from W. E. Strickland, Esq., of England, through Dr. Wilson. Another addition of great value was made by Dr. T. B. Wilson, consisting of one hundred specimens from the collection of the Prince of Canino, C. L. Bonaparte, being the originals of those species figured and described in the Fauna Italica. We are also indebted to Capt. W. McMichael for 7 species, 8 specimens, of animals from Van Dieman's Land. Besides the above there were presented to the Society ten species from various sources. Aves. We have received during the year 71 bird skins, of which 51 are from Van Dieman's Land, presented by Capt. W. McMichael; 10 from China, presented by Capt. John Land; the remainder from various localities, presented by Dr. E. J. Lewis, and others. The valuable Des Murs collection of Bird's eggs, containing 1281 species, mentioned in the last report of the Curators as a deposit, has since been presented to the Academy by Dr. Wilson. To Mr. Samuel Ashmead we are also indebted for the donation of 38 species, 48 specimens of American bird's eggs. There were also presented by various individuals, principally members of the Society, 15 species of nests, and 23 of eggs, from different localities. Reptilia.- Of reptiles there have been received 65 species, 80 specimens, besides numerous American duplicates, principally from Dr. McCartee, of Ningpo, China; Capt. John Land; Mr. Sandwith Drinker, of Hong Kong, China; and Mr. Ashmead. Pisces. In ichthyology the cabinet has received, rather unexpectedly, a large and very valuable collection, presented by Dr. T.B. Wilson, consisting of 767 bottles containing fishes in alcohol, and 177 dried specimens of the latter, formerly belonging to Prince C. L. Bonaparte, and being the originals of the descriptions and illustrations of the Fauna Italica. For list, see Proceedings for January and February, 1850, p. 13. |