CHIROSTOMA. 61 



anterior teeth sometimes moderately strowg ; lower jaw projecting, less than half the length of head ; 

 maxillary exposed distally, extending nearly to the vertical from the anterior margin of eye. 20 or 21 

 gill-rakers on the lower part of the anterior arch. Scales with crenate edges, G8 to 82 in a longitudinal 

 series. Dorsal IV-V, I 10-12; spinous dorsal in advance of anal, its origin usually a little nearer to 

 base of caudal than to tip of snout. Anal I 17-20. Pectoral ^ the length of head, extending to above 

 the base of ventrals. Caudal forked. Caudal peduncle 2| to 3 as long as deep. 



Hab. Mexico, llio Lerma System and the Valley of Mexico : 



Lake Chapala i; Lake Patzcuaro ^ ; Lake Zirahuen (Meek) ; Xochimilcho 3. 



Here described from six specimens, measuring up to 220 mm. in total length, from 

 Lakes Patzcuaro (Mexico Mus.) and Zirahuen (Meek). 



8. Chirostoma cliapalae. 



Chirustoma chapalos, Jord. & Snyd. Bull. U.S. Fish. Comm. xix. 1899, p. 135, fig. 13 (1901) ' ; 

 Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1900, p. 31 59"; Meek, Publ. Columbian Mus., 

 Zool. V. 1904, p. 176, fig. 58 \ 



Depth of body 4^ to bk in the length, length of head 3i to 4i. Snout as long as eye, the diameter of which 

 is 3i to 3| in the length of head and nearly equal to the interorbital width. Teeth small ; lower jaw 

 very slightly projecting ; maxillary very slightly exposed distally, not extending to below the eye. 

 20 to 24 gill-ra.kers on the lower part of anterior arch. Scales with crenate edges, 44 to 51 in a, 

 longitudinal series. Dorsal IIl-V, I 10-11 ; origin of spinous dorsal nearly equidistant from tip of 

 snout and base of caudal ; last dorsal spine inserted above the origin of anal. Anal I lS-21. Pectoral 

 4- or I the length of head, extending to above the middle of the ventrals. Caudal forked. Caudal 

 jiedunele 2 to 2| as long as deep. 



Hah. Mexico, Rio Lerma System : 

 Lake Chapala ^ ^. 



Here described from several specimens from Lake Chapala, measuring up to 

 125 mm. in total leno'th. 



^to- 



9. Chirostoma grandoculis. 



Chirostoma grandoculis, Steind. Denkschr. Ak. Wien, Ixii. 1895, p. 525, t. 2. fig. 1'; Jord. & 

 Everm. Bull. U.S. Nat. Mus. xlvii. 1900, p. 3159'; Meek, Publ. Columbian Mus., Zool. v. 

 1904, p. 176, fig. 58'. 



Depth of body about 5 in the length, length of head 4 to 4j. Snout as long as or shorter than eye, 

 the diameter of which is 34 to 34 in the length of head and equal to the interorbital width. Teeth 

 small ; lower jaw very slightly projecting ; maxillary very slightly exposed distally, not extending to 

 below the eye. 21 to 2:> gill-rakers on the lower part of the anterior arch. Scales with crenate edges, 

 60-62 in a longitudinal series. Dorsal V-Vl, I 10-11 ; spinous dorsal usually entirely in advance of 

 anal, its origin about equidistant from tip of snout and base of caudal. Anal I 17-20. Pectoral | the 

 length of head, extending to above the anterior part or middle of ventrals. Caudal forked. Caudal 

 peduncle 24 to 3 as long as deep. 



Hah. Mexico, Rio Lerma System: 



Lake Chapala ^ ; Lake Patzcuaro ^ ^. 



Here described from four specimens, measuring up to 115 mm. in total length, from 

 Lake Patzcuaro (Mi 



