72 ATHERINID^ : SILVERSIDES 



fin being about two-fifths, instead of one-third, as long as the inter- 

 space between occiput and spinous dorsal ; the eye is larger and the 

 head broader than in young of similar size in the other series men- 

 tioned above (the diameter of the eye and the width of the interorbital 

 are each longer than the snout). Possibly more than one species is 

 included in these several series. 



The dentition of C. arge differs from that of jordani, mezquital, 

 or LABARC.5;. ' The premaxillary teeth are in two series laterally, and 

 about three series anteriorly, where those of the outer series, slightly 

 enlarged throughout, are somewhat longer than those of the inner series.. 



117. Chirostoma bartoni Jordan and Evermann, 1896.-^'- 



(Plate VI, Fig. 24) 



Chirostoma humboldtianum Jordan, Proc. U. S. Nat. Mus., 2, 299, 1879 (not 



Atherina humboldtiana Cuvier and Valenciennes). 

 Chirostoma bartoni Jordan and Evermann, Bull. U. S. Nat. Mus., 47, pt. 1, 793, 

 1896; Evermann and Goldsborough, Bull. U. S. Fish Comm., 21, 152, 1901 

 (1902) ; Meek, Publ. Field Mus. (Zool), 3, 112, 1902; 5, 172, 1904; Regan, 

 Biol. Centr.-Amer. Pisces, 58, 1907 (in part). 

 Eslopsarum bartoni Jordan and Evermann, Bull. U. S. Nat. Mus., 47, pt. 3, 



2840, 1898. 

 Type-locality. — A tributary of the Rio Lerma, near Guanajuato, Mexico. 

 Chirostoma attenuatum Meek, Publ. Field Mus. (Zool.) 3, 112, pi. 2, 1902; 

 5, 172, fig. 55, 1904. 

 Type-locality. — Lago de Patzcuaro, Michoacan, Mexico. 

 Range. — Tributaries of the Lerma River, Lake Lerma, and Patzcuaro, Mexico. 



Mr. Regan was certainly in error in referring the more finely scaled 

 C. ziR.\HUEN to this species. He seems to have been correct, however, 

 in assigning attenu.\tum to bartoni, as a reexamination of Dr. Meek's 

 material indicates. The specimens of bartoni from Lake Lerma and 

 the Lerma fish-hatchery have the spinous dorsal in the same position 

 as in the types of attenuatum from Lake Patzcuaro ; in both series the 

 soft anal rays vary from 13 to 15. 



The fine teeth of bartoni are biserially arranged in the jaws. The 

 teeth of the outer mandibular series are curved and slightly enlarged ; 

 those of the two premaxillary series are of subequal size, slightly 

 enlarged in the inner series near front of jaws. 



118. Chirostoma zirahuen Meek, 1902.-^*- 



(Plate VII. Fig. 25) 



Chirostoma zirahuen Meek. Publ. Field Mus. (Zool.), 3, 114, pi. 28, 1902; 5, 174, 



fig. 57, 1904. 



Type-locality. — Lago de Zirahuen, Zirahuen, Michoacan, Mexico. 



Chirostoma bartoni Regan, Biol. Centr.-Amer., Pisces, 58, pi. 10, fig. 2, 1907 (in 



part) (not of Jordan and Evermann). 

 Range. — Lake Zirahuen, Mexico. 



