ZOOGONETICUS.—LIMNURGUS. 87 
Zoogoneticus robustus, Meck, Publ. Columbian Mus., Zool. iii. 1902, p. 92°, and v. 1904, p. 113, 
fig. 31°. 
Zoogoneticus maculatus, Regan, Ann, Mag. N. H. (7) xiii. 1904, p. 256°. 
Depth of body 3 to 32 in the length, length of head 3 to 31. Snout as long as or longer than eye, the 
diameter of which is 4 to 5 in the length of head; interorbital width 21 to 22 in the length of head. 
Lower jaw projecting. 36 to 39 scales in a longitudinal series. Dorsal 18-14; origin nearly equidistant 
from preoperculum and base of caudal. Anal 14-16; origin a little behind that of the dorsal. Pectoral 
3 to % the length of head. Caudal subtruncate. Body usually with irregular dark spots; fins 
immaculate. 
Hab. Mexico, Rio Lerma System : 
Guanajuato!; Rio Grande de Santiago® (Buller); Lake Chapala?4; Lake 
Cuitzeo?4; Lake Patzcuaro24; Zirahuen ? 4. 
Here described from several specimens from the Rio Grande de Santiago, Lake 
Chapala, and Lake Patzcuaro, measuring up to 145 mm. in total length. 
6. LIMNURGUS, Ginth., 1866. 
Limnurgus, Giinth. Cat. Fish. vi. p. 8309 (1866). 
Girardinichthys, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 666. 
Viviparous. Anal fin of the male with the anterior five or six rays short, stiff, and subequal, separated by a 
more or less distinct notch from the rest of the fin. Mouth small, with short lateral cleft; rami of the 
lower jaw firmly united ; minute teeth in bands, with an outer series of enlarged fixed teeth which are 
usually spear-shaped, but may have their apices truncate or even notched. 
A single species from the Valley of Mexico. 
1. Limnurgus innominatus. (Tab. XII. fig. 1.) 
Lucania sp., Girard, Proc. Ac. Philad. 1859, p. 118°. 
Girardinichthys innominatus, Bleek. Cyprin. p. 484 (1860) *; Jord. & Everm. Bull. U.S. Nat. Mus. 
xlvil. 1896, p. 666°; Meek, Publ. Columbian Mus., Zool. v. 1904, p. 116 *. 
Limnurgus variegatus, Giinth. Cat. Fish. vi. p. 309 (1866) °*. 
Characodon geddesi, Regan, Ann. Mag. N. H. (7) xiii. 1904, p. 257°. 
Depth of body 23 to 33 in the length, length of head 3? to 4. Snout as long as eye, the diameter of which 
is 4 to 44 in the length of head; interorbital width 2} to 22 in the length of head. 39 to 48 scales in 
a longitudinal series. Dorsal 18-23; origin equidistant from eye (d) or operculum (2) and base of 
caudal. Anal 20-26 ; origin a little behind that of the dorsal. Pectoral 2 the length of head. Caudal 
subtruncate. Body with irregular dark spots or narrow vertical bars. 
Hab. Mexico, Valley of Mexico: 
City of Mexico!; Lake Chalco* (Meek); Lake Tezcoco® (Geddes) ; 
Xochimilco ¢. 
Here described from several specimens, measuring up to 7) mm. in total 
length. 
