96 PROCEEDINGS OF THE ACADEMY OF 



ventrals are inserted midway between the branchial apertures and the base of 

 the caudal. The caudal is forked. 



Color greyish, tinged with silvery on the sides. 



The species is eminently distinguished from its congeners by the form of 

 the dorsal buckler; it is most nearly related to C. megalops. P >: ?3R 



I dedicate this species to the meritorious ichthyologist and herpetologist 

 Dr. Franz Steindachner, as a slight recognition of his labors. 



Sept. 6th. 



Mr. Vaux, Vice-President, in the Chair. 



Seventeen members present. 



The following paper was presented for publication : 

 "Notice of some Crustaceans of the Genus Libinia, with descrip- 

 tions of three new species." By T. Hale Streets. 



Prof. Leidy stated that he had just returned from a short visit to Boston 

 and Cambridge, and that while there be had had the opportunity of examining 

 the collection of Mastodon remains of the Warren museum and the Cambridge 

 University museum, which had so much interested him, that he thought a brief 

 notice of them would be interesting to the members. 



The private museum of the late Dr. Warren, now in possession of his heirs, 

 contains a magnificent skeleton of the American Mastodon [M. america?ms) , 

 the best preserved and most complete which has yet been found. It was dis- 

 covered in 1845, at Newburgh, N. Y. It is that of a mature male. The jaws 

 contain the last two molars on both sides, besides the tusks above, and one of 

 those below, together with the alveolus of that of the opposite side. This 

 skeleton forms the basis of Warren's book on the Mastodon, published in 

 1852. 



Besides the skeleton indicated, Dr. Warren's museum contains the skull of 

 another, a well preserved specimen, found in Orange Co., X. Y. It is even 

 larger than that of the skeleton, and also pertained to a mature male. The 

 jaws. contain on both sides the last two molars; and on one side the fourth 

 molar is also retained. The specimen is described and figured in Warren's 

 book on the Mastodon. (Pis. xvi, xviii, xix.) 



The Warren collection further contains a number of other remains of Mas- 

 todon, mainly fragments of jaws with teeth, isolated molars, and casts in 

 plaster of others. I may add it also contains a number of molars of the 

 American Elephant (Elephas americanus), together with many vertebne of the 

 Basilosaurus. 



The museum of the University of Cambridge contains the most interesting 

 series of remains of the American Mastodon which I have yet seen collected 

 together in one place. The most important of these are as follow: 



1. A skeleton, discovered, in 1844, in Warren Co., N. J. It pertams to a 

 mature female. The jaws contain the last two molars on both sides, and no 

 traces of inferior tusks remain. 



2. A complete skull of what I take to have been a female approaching 

 maturity. The jaws contain the fourth and fifth molars in functional position. 

 The sixth molar had not protruded and is visible within the jaws. On one 

 side of the lower jaw the third molar is retained but is nearly worn out. On 

 the other side and in the upper jaw the alveoli of the corresponding teeth are 

 partially obliterated. The incisive sockets of the lower jaw are likewise ob- 

 literated. (The specimen is represented in plates v, vi, of Warren's book on 

 the Mastodon.) 



3. Another complete skull of an animal younger than that of the preceding 



[Sept. 



