150 PROCEEDINGS OF THE ACADEMY OF 



ville, Chester Co. The Posidonice Mr. Conrad regards as identical with the 

 P. multicostata and P. triangularis of Prof. Emmons, obtained from a corres- 

 ponding geological formation of Chatham Co., N. C* The former species had 

 been previously indicated by Mr. Lea under the name of P. ovata-f from speci- 

 mens obtained at Phoenixville, and probably the latter was also indicated under 

 the name oi P.parva from smaller specimens than those presented this evening, 

 but likewise obtained from the same locality. 



The dental bone referred to, apparently belongs to a ganoid fish, probably 

 allied to Eugnathus or Belonosiomus. 



Dr. L. further observed that Prof. Emmons had recently discovered the re- 

 mains of an insectivorous mammal in the same series of rocks of Chatham Co., 

 X. C.{ The animal, Dromatherium sylvestre, is closely allied to the Spalacothe- 

 rium, Owen, from the English Purbeck beds of the oolitic series, and it may pro- 

 bably indicate that the rocks in which it was found, with those corresponding 

 in this State, may be of the same age as those of the Richmond coal field. 



The Clepsysaurvs, Lea, of the same rocks of Pennsylvania and North Carolina, 

 is not properly a thecodent reptile, but may form the type of a new family, as 

 its teeth are inserted in the jaw by solid conical fangs. Omosaurus of the same 

 formations is probably a distinct genus from Clepsysaurus. 



Mr. Cassin announced the death of Lieut. J. C. Strain, late a Cor- 

 respondent of the Academy. 



June IQth, 1857. 



Dr. T. B. Wilson in the Chair. 



The following papers were offered for publication, viz : 

 Notices of the Remains of extinct Fishes, by J. Leidy, M. D. 

 Description of a new species of Myacites, by T. A. Conrad. 

 Description of a new genus of the family Dreissenidee, by T. A. 

 Conrad. 



Examination of Enargite, from New Grenada, by W. J. Taylor. 



Which were referred to Committees. 



Dr. Leidy read a letter fom Dr. J. S. Newberry, dated Washington, 



D. C., May 4, 1857, desiring that the title Mekolepis, applied by him 

 to a genus of fossil fish, be changed to Eurylepis, the former having been 

 anticipated by Dumeril and Bibron. The species would then read 

 Eurylepis corrugatus ; E. tuherculatus ; E. gramdahis ; E. lineatus ; 



E. ovoideus J E. 07'natissimus ; E. insculptus ; E. scrratus. 



Dr. Leidy exhibited specimens of New Red Sandstone fossils from 

 near the Gwyned tunnel, on the North Pennsylvania Railroad, collected 

 by Mr. Lea and himself. These are species of Cypris, very numerous, 

 some scales of Ganoid fishes, and remains of bones and teeth, probably 

 Batrachian. 



Dr. Morris called the attention of the Academy to some fishes kept 

 in a vase where water was not removed frequently enough ; the fishes 

 then rise at short intervals to the surface and swallow air, thus main- 

 taining their respiration ; showing that the exchange of gases in this 

 class of animals takes place readily as long as the branchiae are kept 

 moist, and illustrating the mode of respiration in the genus Anabas. 



* Geol. Rep. of North Carolina, 1856, p. 337. 

 tProc. A. N. S. viii. 78. April, 1856. 

 X American Geology, pt. vi. p. 93. 



[June, 



