112 proceedings of the academy of 



May 9. 



The President, Dr. Ruschenberger, in the chair. 



Twenty-four members present. 



The following paper was offered for publication : — 



" Notes on the Natural History of Fort Macon. No. 2." By 

 Elliott Coues. 



Prof. Leidy said that he had just received, from its author, 

 Mr. Mason, a copy of an abstract from the proceedings of the 

 Asiatic Society of Bengal, for June, 1811, giving an account of a 

 case of polydactylism in a horse from Bagdad. In this case the 

 usual " splint-like rudiments of the metacarpals of the fourth toe 

 in the fore feet had given rise to an additional toe provided with 

 three phalanges, of which the last is incased in a hoof." A pre- 

 paration of the foot of a horse, preserved in the Museum of the 

 Universit}'^ of Pennsylvania, exhibits a similar condition. The 

 abnormally developed metacarj^al has the toe with two phalanges, 

 of which the last is inclosed in an irregular hoof. If there were a 

 corresponding development of the metacarpal on the other side 

 of the preparation, the foot would represent the normal condition 

 of the tertiary horse Hipparion. If both outer toes were still 

 better developed in relation with the intermediate one, the foot 

 would represent the condition of the earlier tertiary horse Anchi- 

 therium. 



Prof. Cope demonstrated some anatomical points of import- 

 ance in the classification of some of the Siluroids of the Amazon, 

 noticing first those which have no swimming-bladder, but having 

 the post-temporal bone pierced in a sieve-like manner, forming 

 minute tympana; these he characterized as '■'■ OtocinclusJ^ 



Others having huge swim-bladders, gun-boat style of shape. 

 No adipose fin ; the back naked. No lyre plate ; indicated as 

 ^^ Zathorax.'' 



A 3d, body protected by bonj' shields above. No adipose fin ; 

 the scapular arch dermoossified and lyre-shaped below ; indicated 

 as ^''PJujsopyxis Jyra.'" 



A 4th, shielded all over its sides, with the under lip turned 

 back, genus '■'■ Corydoras.^^ 



A 5th, where the under lip is separated, except at the ends, 

 forming loops, named ^'■Jjrochis.^' 



In the Gtb, Avhere the lips are separated from the beard distally 

 forming chin beards, indicated as '■'• Dianema.''^ 



Lieutenant Dutton remarked that the persistence and con- 

 stancy of specific characters, while generic features were under- 

 going change, was admirabl}- illustrated in some of the genera of 

 Brachiopoda in the Silurian and Devonian. These genera are 



[July 11, 



