298 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Length, 57 millimeters; height from base to umbo, 

 thickness, both valves together, 24 millimeters. 



In general aspect this shell approaches T, prouti Meek & Hayden, 

 from the Upper Fox Hills Group of the Upper Missouri Eiver region^ 

 but it differs in being proportionally narrower and more produced be- 

 hind the beaks, and in the greater prominence of the umbones. 



Position and locality. — Cretaceous strata, Bell County, Texas, where 

 it was collected by Mr. D. H. Walker. 



Washington, Becemher 4, 1879. 



NOTES ON ACOtiliECTIOlV OF FISHES OBTAIIVED I!V THE STREAinS 

 OF GUAIVAJtATO AND IN CHAPAI.A I^AKE, 9IEXI€0, BY PROF. A 

 DUOES. 



By DATID S. JORDAIV.^ 



The collection which forms the subject of this paper was obtained 

 by Prof. A. Duges in the streams of the province of Guanajuato in 

 Mexico, and by him forwarded to the Smithsonian Institution. Many 

 of them are extremely interesting as rei)resenting the ordinary North 

 American fish fauna at a point near its southern limit, before it gives 

 place to the Central and South American forms. 



Chirostoma estor Jordan, sp. uov. 



Allied to Chirostoma humholdtianum (C. & Y.). 



Body elongate but rather robust for the genus, the depth about one- 

 sixth the length to the base of the caudal. 



Head very large, pike-like, forming more than one-fourth (two- 

 sevenths) the length to base of caudal. 



Mouth very large, the maxillary reaching to past the front of the eye. 

 Intermaxillaries forming the edge of the jaw strongly curved, their pos- 

 terior portions broadly dilated as in Chirostoma menidium. Teeth strong, 

 in several series in each jaw. Two small fang-like teeth on the front of 

 the vomer. Lower jaw considerably projecting beyond the upper. Eye 

 large, anterior, 5 in length of head, shorter than snout, and a little nar- 

 rower than the interorbital space, which is nearly flat. 



Head covered with scales, which are smallest bn the occipital region, 

 and largest on the lower part of the cheeks. Smaller scales on the inter- 

 opercle. 



Sides of head vertical, a conspicuous ridge along the edge of the top 

 of the head above and behind the eye. 



Scales small, anteriorly crowded, about 72 in a longitudinal series, 

 and 18 in a cross series. Posterior margin of scales strongly crenate, 

 so that the fish feels rough to the touch. 



* As Professor Jordan is far distant while this paper is going through the press, the 

 proof has been compared with his manuscript by the editor of these Proceedings. In 

 the de8crij)tion of Zoj)hendum australe two verbal additions are indicated in pareu- 



