MAY, 1902. THK ICHTHYOLOGY OF MEXICO -MEEK. 87 



Mexico, or in the Lerma Basin. It is quite probable that Fil- 

 ippi's specimens came from some stream east of .Mexico City. 



Dr. Bocourt in Annales des Sciences Nat., 1862, gives a short 

 account of several supposed new species of Tetragonopterus 

 which evidently do not exist. The number of anal rays of this 

 species varies from 20 to 23. It is perhaps a little less slender 

 than T. argentatus, though the large series of specimens before 

 me rather suggests that this and the preceding species are the 

 same. In color and size both species are alike. 



The stomach of one specimen from Cuicatlan contained a 

 good-sized Heterandia. All of the specimens we have from the 

 southern rivers of Mexico belong to one species. 



This species seldom exceeds 4 inches in length. Abundant; 

 our specimens from Puente de Ixtla; Balsas; Cuicatlan; Venta 

 Salada. 



DOROSOMATID^E. 



Dorosoma mexicanum (Gunther). 



N - 



Two small specimens from La Antigua. 



ENGRAULID.^. 



Stolephorus mitchilli (C. & V.) 



Two small specimens from La Antigua. 



PCECILIID.E. 



1 was very fortunate in collecting the representatives of this fam- 

 ily in Mexico during the breeding season. It was rather surprising to 

 find so many of them viviparous. The fact that the anal fin of the 

 male of many of the species of this family is not modified into a 

 long slender intromittent organ, such as we find in Gambusia, Heter- 

 andia and the like, was regarded as sufficient evidence that they were 

 not viviparous. 



The shortening of the first half dozen rays of the anal fin in the 

 male and their slight separation from the rest of the fin by a notch was 

 first noticed by Dr. Gunther in CJiaracodon lateralis. It was also 

 described by Dr. Bean in Zoogoncticus robust us, and by Jordan and Sny- 

 der in Goodea caliente. Dr. Bean supposed it to'be characteristic of the 

 female. This peculiar modification of the anal fin of the male exists 

 in several genera of viviparous cyprinodonts. 



Evermann and Goldsborough, in a recent paper on Mexican fishes 

 call attention to the fact that Girardinichtliys i/m<niti<.itus is vivipar- 



