302 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



DESCRIPTIOIVS OF VWO HP'ECl'EH OF FI$4IIFS COIiliFCTED BIT PROF. 

 A. D1J«^S IN C'ENTRAl, 9IEXICO. 



By TARI.ETOJ¥ H. BEAN. 



The larger portion of the fishes presented to the United States National 

 Museum by Professor Duges in June, 1879, have been reported upon by- 

 Prof. D. S. Jordan in a previous paper of these Proceedings.* In all 8 

 species were transmitted by Professor Duges, 4 of them being described 

 in the article just mentioned and 2 in the present paper as new to science. 



The discovery of Myxostoma and Amiurus in streams which flow into 

 the Pacific is singular and interesting, and, at the same time, the occur- 

 rence of additional genera, ZopJiendum and Hudsonius, characteristic of 

 the Eastern United States, makes it desirable to know more of the 

 chmatic and statigraphic conditions existing in Guanajuato and adjoin- 

 ing provinces. Goodea and two of the Chirostomas are from a salt lake 

 in the middle of a little volcanic plain in Valle de Santiago^ Guanajuato. 



Myxostoma austrina Beau, sp. nov. 



The type specimens were collected at Piedad, in Morelia (Michoacan), 

 Mexico. They are numbered 23120 and 23121 in the United States Na- 

 tional Museum catalogue. The species may belong to Minytrema rather 

 than Myxostoma^ but in the absence of all the abdominal viscera this 

 point cannot now be settled. It has a remarkably small fontanelle. 



Description. — Body not elongate, rather stout. Lips plicate, trun- 

 cate or slightly rounded behind. 



The greatest height of the body equals about i, and the least height 

 of the tail -^ of the length of body.t 



The length of the head (,23-.24) is contained 4^ times in length of 

 body. Its width (.15) equals the length of the base of the dorsal. The 

 interorbital distance (.095) equals the length of the snout. The length 

 of the operculum (.07-.075) equals ^ the length of the ventral. The long 

 diameter of the eye (.04) is contained G times in the length of the side 

 of the head. 



The distance of the dorsal from the snout (.45) equals 3 times the 

 length of its base; the beginning of the dorsal is equally distant from 

 the tip of the snout and the end of the anal. The longest dorsal ray 

 (.16) is twice as long as the last (.08), and its length is contained 5 times 

 in the distance of the anal from the snout. 



The length of the base of the anal (.085-.09) is contained twice in the 

 distance from the snout to the nape. The longest anal ray (.22) equals 

 in length the external caudal rays, measuring these from the origin of 

 the middle caudal rays. The last ray of the anal is as long as the snoutt 



The length of the middle caudal rays (.13) equals about ^ the height 

 of the body. 



The distance of the pectoral from the snout (.25) is contained 4 times 



*Proc. U. S. Nat. Miis., vol. ii, p. 298. 



t Length of body is to be understood as length without the caudal. 



