CO PERCESOCES. 



the diametor of which is 3| to -4 in the length of head ; intororbital width 3 to 3^ in the length of head 

 Teeth small ; lower jaw slightlj- proieoting ; maxillary slightly exposed distally, not quite reaching the- 

 Tertical from the anterior margin of eye. 15 or 16 gill-rakers on the lower part of the anterior arch. 

 Scales with crenate edges, (38) 40 to 4.3 in a longitudinal scries. Dorsal III-V, I 9-11 ; origin of 

 spinous dorsal usually nearer to base of caudal than to tip of snout ; last dorsal spine inserted a little 

 in advance of the origin of anal, which is below the nierabranc connecting the spine to the back. 

 Anal I 17-20 (21). Pectoral ^ to i the length of head, extending a little beyond the base of ventrals. 

 Caudal forked. Caudal peduncle 2 to 2^ as long as deep. 



Ilab. Mexico, Rio Lerma System ami the Valley of Mexico: 

 Lake Chapala ^ ; Lake Cuitzeo ^ ; Xochimilco. 



Here described from fottr specimens from Xochimiico {Jleel'), measuring up to 

 100 mm. in total length. 



6. CMrostoma humboldtianum. 



Atherina humboldtiana, Cuv. & Yal. Hist. Nat. Poiss, x. p. 479, t. 306 (1835) '. 



Atherina vomerina, Cuv. & Val. t. c. p, 481 ^. 



Atherinichthys Immboldiii, GLinth. Cat. Fisli. iii. p. 404 (1861) ^ 



Chirostoma liumboldtianum, Steind. Dciiksclir. Ak. Wiei), Ixii. 1895, p. 5.22, t. 1, fii;;. 1': 



.lord. & Everm. Bull. U.S. Nat. Mus, xlvii. 1896, p. 793''; Jord. & Siiyd. Bull. U.S. Fisli. 



Comm. xix. 1899, p. 134" ; Meek, Publ. Columbian Mus., Zool. v. 1904, p. 17:)''. 



Depth of body 4 to 5j in the length, length of head 3-1 to 4. Snout from as long to twice as long as the eye, 

 the diameter of which is 3| to 5| in the length of head ; interorbital width 3| to 3| in the length of 

 head. Teeth rather small ; jaws equal anterioidy or the lower a little projecting ; lower jaw less than 

 i the length of head ; maxillary exposed distally, extending nearly to the vertical from the anterior 

 margin of eye. 10 to 19 gill-rakers on the lower part of the anterior arch. Scales with edges usually 

 crenate ; 48 to 62 in a longitudinal series. Dorsal IV- VI, I 10-13 ; 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 -n- to 4 

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

 peduncle 2 to 2ij as long as deep. 



Hah. Mexico, Rio Lerma System and the Valley of Mexico : 



Lake Juanacatlan^ {Biiller) ; Lake Ayotla (Btdler) ; Lake Patzcuaro " ; City of 

 Mexico ^ (Dooymem) ; Texcoco -* ; Lake Chalco '^ '^ (Jordan); Xochimilco* {Meek, 

 Gadow). 



Here described from a large series of specimens, measuring up to 240 mm. io 

 total length. Dr. P. Pappenheim has very kitidly examined the type of the species 

 on my behalf and has sent me a photograph of it, which leaves uo doubt that the 

 species above described is the true C. Iminboldtkumm. 



7. Chirostoma estor. 



CInrostorna estor, .lord. Proc. U.S. Nat. Mus. 1879, p. 298'; Steuid. Denkschr. Ak. Wien, Ixii. 



1895, p. 533, t. 1. fig. 2 = ; Meek, Pub!. Columbian iMus., Zool. v. 1904, p. 180 '. 

 Lelhoslde cf>lor, .lord. & lilverai. Pull. U.S. Nat. Mus. xlvii. 1890, p. 792*. 



Depth of liody about 5 in the length, length of head 2>h to 4. Snout l.i to 2 as long as eye, the diameter of 

 which is 4 to 5j in the length of head; interorbital width 4 ii.t the length of head. Teeth small-. 



wt 



