MAY, 1902. THE ICHTHYOLOGY OF MEXICO MEEK. 115 



Mexico. It is one of the largest species of the genus, though it 

 seldom reaches a length of 12 inches. Specimens from Lago 

 de Chalco are very dark, while those from Lago de Patzcuaro are 

 very light and translucent. Specimens from Lago de Xochomil- 

 cho are intermediate. Scales entire; gill-rakers 5-1-13= 18; verte- 

 brae 234-19 = 42; teeth small, in a narrow band in upper jaw, in 

 two series in the lower. There are often with a few large teeth 

 on the vomer, as in C. estor. 



The ovaries not well developed; eggs small, spawning season 

 evidently late in the summer. Chalco; Xochomilcho; Patzcuaro. 



Chirostoma chapalse Jordan & Snyder. 



This species is very white and translucent. It is'a small spe- 

 cies, seldom reaching a length of 4 inches. Edges of scales 

 crenate; gill-rakers 64-24 = 30; vertebrae 24+20 = 44. Very abun- 

 dant in Lago de Chapala. Ocotlan; La Palma. 



Chirostoma grandocule Steindachner. 



Edges of scales crenate; base of anal fin ijjin length of the 

 head, its rays 19; snout 3| in head; mandible 2^; eye 3^; teeth 

 minute, in narrow bands on each jaw, approaching two series 

 laterally; gill-rakers 54-22 = 27; vertebrae 234-20=43; species of 

 small size, the largest specimens about 4^ inches. This appears 

 to be the most abundant Cliirostoma in Patzcuaro Lake. Ocotlan; 

 La Palma; Patzcuaro. 



Chirostoma promelas Jordan & Snyder. 



This is the only species of Chirostoma so far known which has 

 the upper jaw decidedly longer than the lower. The tip of the 

 snout is black, otherwise the color is light and translucent. 

 Edges of scales crenate; gill-rakers 54-19 = 24. This species is not 

 abundant; size medium. Our largest specimen is 4^ inches in 

 length. The longest specimen collected by Jordan & Snyder is 7 

 inches in length. Ocotlan; La Palma. 



Chirostoma lucius Boulenger. 



This is evidently the species described by Jordan & Snyder as 

 C. crystalinuin in a foot-note * Dr. Jordan expressed the opinion 

 that C. lucius is identical with C. Icrnnc. The teeth of C Indus 

 are described as small, while C. lernnc has very large strong teeth. 



I* Bui. U. S. F. C. 19DO, 2S7.I 



