XXXII. CHIROSTOMA 71 



caudal and a point varying from more than the length of the eye behind 

 the snout, to a little more than half length of eye before snout. C. mez- 

 QUiTAL is perhaps quite as closely related to C. arge, but is likewise 

 distinct from it. 



In C. MEZQUITAL the teeth are disposed rather definitely in two 

 series in the jaws, those of the outer mandibular and inner premaxil- 

 lary series slightly enlarged. The teeth erroneously said to be uniserial 

 in the type description. 



115. Chirostoma labarcae Meek, 1902.^*- 



(Plate VI, Fig. 22) 



Chirostoma labarg^ Meek, Publ. Field Mus. (Zool), 3, 113, pi. 27, 1902; 5, 173, 



1904. 



Type-locality. — Rio Lerma at La Barca, Jalisco, Mexico. 



Chirostoma brev'e Regan, Biol. Centr.-Amer., Pisces, 59, 1907 (in part; not of 



Steindachner). 

 Range. — Vicinity of Lake Chapala, Mexico (known only from La Barca and 

 La Palma). 



This very distinct species is identical neither with breve (=jor- 

 DANi), as Mr. Regan suggested, nor with the species (regani) which 

 he described under the name breve. It is perhaps most closely related 

 to C. jORDANi, which is the only other species in which the first dorsal 

 fin begins over the origin of the anal. It dififers from jordani, as well 

 as from all other large-scaled species of the. genus, in the long and 

 acutely pointed snout. 



The dentition of this species has not been accurately described. The 

 teeth are in two irregular series in both jaws ; those of the outer series 

 in the mandible are enlarged ; those of the inner premaxillary series 

 become canine-like toward the front of the jaws. 



116. Chirostoma arge (Jordan and Snyder), 1900."^*- 

 (Plate VI, Fig. 23) 

 EsLOPSARUM ARGE Jordan and Snyder, Bull. U. S. Fish Comm., 19, 133, fig. 12, 1899 

 (1900) ; Jordan and Evermann, Bull. U. S. Nat. Mus., 47, pt. 4, 3158, 1900. 

 Chirostoma arge Meek, Publ. Field Mus. (Zool), 3, 112, 1902; 5, 171, fig. 54, 



1904; 7, 156, 1907; Regan, Biol.-Centr.-Amer., Pisces, 59, 1907. 

 Type-locality. — Rio Verde, near Aguas Calientes, Mexico. 

 Range. — Rio Verde and Rio Lerma, and their tributaries, Mexico (not known from 

 the lakes). 



Topotypes of C. arge from Aguas Calientes and Lagos (also in 

 the Rio Verde Basin) are more slender than the holotype. Others from 

 San Miguel de Allende, taken in a tributary to the Rio Lerma, are 

 more robust in form; in these specimens the pectoral fins are usually 

 but not always longer, and all of the fins much more deeply pigment, 

 than in the topotypes. Five young specimens from Salamanca, included 

 in the type lot of C. jordani Woolman, have a still longer pectoral, this 



