STUDIES OF THE FISHES OF THE ORDER CYPRINODONTES 



By Carl L. Hubbs 



I. A Cl^ASSlFl CATION OF THE) FlSH^S OF THE OrdER 



II. An Analysis of the Genera of the Poeciliidae 



III. The Species of Profundulus, a new Genus from Central 



America 



IV. The Subspecies of Pseudoxiphophorus bimaculatus and of Pria- 



pichthys annectens 



I. A Classification of the Fishes of the Order 



The order Cyprinodontes Agassiz (equivalent to Microcyprini Regan) 

 comprises certain fishes which have in the past been more or less confused, 

 first with the Cyprinidae, then later with the Haplomi (Esox, Umbra, Dallia). 

 Toward each of these groups the Cyprinodontes show, indeed, a superficial 

 resemblance, but this resemblance is apparently not indicative of genetic 

 relationship. 



It has long been clear that these fishes have no close affinity with the 

 cyprinids, but not until 191 1 was their close relationship with the Haplomi 

 critically questioned.^ 



It appears probable, in reference to the main line of evolution of fishes, 

 that the Cyprinodontes are of distinctly more advanced organization than the 

 Haplomi. They differ from the Haplomi and most other primitive orders 

 of fishes, and resemble the acanthopterygian fishes in the following respects : 



1. The premaxillaries alone form the margin of the upper jaw. 



2. The pectoral fin is elevated in position, and the base of the fin is lat- 

 eral and vertical, rather than ventral and transverse (in Dallia alone among 

 the Haplomi the pectoral fin resembles that of the Cyprinodontes, but in that 

 genus the basal bones are highly modified : the resemblance is not indicative 

 of relationship). 



3. The pelvic fins are more anteriorly inserted. 



4. The pelvic rays are not more than 6 in number. 



5. The vertebrae are typically reduced in number. 



6. The larval adhesive organ, which the writer has found retained in 

 Esox lucius of the Haplomi, is apparently never developed in any of the 

 Cyprinodontes. 



1 Regan, Ann. Mag. Nat. Hist., 7, 191 1, p. 323. 



