NATURAL SCIENCES OF PHILADELPHIA. 



the animals also differ, and the crowning evidence of this distinction in a spe- 

 cific point of view, is the absence of all intermediate forms and varieties, each 

 species preserving its integrity, under the operation of the same law that pre- 

 serves the purity of species of Unio, where from 30 to 50 species are found in 

 one stream, as is seen in some of the western rivers." 



January 29(7i. 

 Mr. Lea, President, in the Chair. 



Thirty-three members present. 



On report of the respective Committees, the following papers were 

 ordered to be published in the Proceedings : 



Description of a new Species of the Genus ANABLEPS of Gronovius. 



BY THEODORE GILL. 







There has recently been sent to the Smithsonian Institution from Panama, 



by Captain J. M. Dow, a new species of the genus Anableps. The number of 

 the species of the genus is now increased to four, all of which, with the excep- 

 tion of the one now to be described, are from the Caribbean Sea, along ihe 

 northern coast of South America. 



Preliminary to a description of the new species, we give a diagnosis of itib 

 genus, in order not to be obliged to insert as specific characters those which 

 are really generic. 



Subfamily ANABLEPTIN^E Gill. 



Genus Anableps (Artedi) Gronovius. 

 Synonymy. 

 Anableps Artedi, Linn., in first editions of Systema Naturae. 

 Cobitis sp. Linn., in later editions of Systema Naturae. 



Anableps Gronovius Zoophylacium. 



Body elongated, anteriorly depressed, posteriorly compressed. 



Scales moderate or small, cycloid, covering almost the entire head and bodv; 

 those on the head, anterior to the nape, larger and less imbricated. The base 

 of the caudal fin and the anal appendage of the male are also covered with 

 scales. 



Head depressed, cuneiform in profile, oblong above, gradually diminishing in 

 width to the snout. 



Mouth anterior and transverse, opening downwards and forwards. Upper 

 jaw projecting beyond the lower. Intermaxillary bones with the ascending pro- 

 cess represented by simple knobs. Maxillaries entirely lateral, and excluded 

 from the composition of the mouth, Dentary flattened. 



Teeth acute, only on the intermaxillaries and dentaries ; in the former in a 

 broad band, the anterior ones larger and moveable, as in Pozcilia; the posterior 

 villiform and immoveable. Those of the lower jaw nearly horizontal aud princi- 

 pally in one row on the front of the dentaries. 



Eyes situated in the anterior half of the head, oblique, and protected by the 

 elevated arches of the frontal bones. The cornea and iris are divided into two 

 more or less unequal portions by a horizontal band. 



Nostrils double ; the anterior at the anterior and inferior edge of the nasal 

 bones ; the posterior oblique fissures in front of the eyes. 



Branchiostegal membrane deeply excavated, the fissure extending to the an- 

 terior borders of the eyes. Branchiostegal rays five. 



Dorsal fin higher than long, situated far behind, between the anal and caudal. 



Anal in the females of nearly the same form as the dorsal ; in the males with 

 a large conical appendage in front. 



1861] 



