CHIROSTOMA. 61 
anterior teeth sometimes moderately strong ; 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, 68 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 2 the length of head, extending to above 
the base of ventrals. Caudal forked. Caudal peduncle 23 to 3 as long as deep. 
Hab. Muxico, Rio Lerma System and the Valley of Mexico: 
Lake Chapala’; Lake Patzcuaro?; Lake Zirahuen (Meek); Xochimilcho °. 
Here described from six specimens, measuring up to 220 mm. in total length, from 
Lakes Patzcuaro (Mexico Mus.) and Zirahuen (Meek). 
8. Chirostoma chapalea. 
Chirostoma chapale, Jord. & Snyd. Bull. U.S. Fish. Comm. xix. 1899, p. 135, fig. 13 (1901) '; 
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 43 to 53 in the length, length of head 34 to 43. Snout as long as eye, the diameter of which 
is 34 to 33 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-rakers on the lower part of anterior arch. Scales with crenate edges, 44 to 51 in a 
longitudinal series. Dorsal ITI-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 18-21. Pectoral 
4 or 2 the length of head, extending to above the middle of the ventrals. Caudal forked. Caudal 
peduncle 2 to 24 as long as deep. 
Hab. Mexico, Rio Lerma System : 
Lake Chapala ! °, 
Here described from several specimens from Lake Chapala, measuring up to 
125 mm. in total length. 
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. 81597; Meek, Publ. Columbian Mus., Zool. v. 
1904, p. 176, fig. 58°. 
Depth of body about 5 in the length, length of head 4 to 44. 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 23 gill-rakers on the lower part of the anterior arch. Scales with crenate edges, 
56-62 in a longitudinal series, Dorsal V-VI, 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 2 the 
length of head, extending to above the anterior part or middle of ventrals. Caudal forked. Caudal 
peduncle 23 to 3 as long as deep. 
Hab. Mexico, Rio Lerma System: 
Lake Chapala*; Lake Patzcuaro !3, 
Here described from four specimens, measuring up to 115 mm. in total length, from 
Lake Patzcuaro (Mees). 
