THE CYPRINODONTS. 143 



CYNOLEBIAS. 



Cpwlebias Steind., 1876, Sb. Ak. Wien, LXXIV, extr. p. 124. 



Head and body compressed, body deep, caudal pedicel medium. Chin 

 steep, lower jaw massive, prominent, symphyses firm. Teeth subconical, in 

 bands. Gill openings wide ; membranes short, united for a short distance, 

 free from the isthmus. Dorsal and anal with numerous rays, opposed, anal 

 longer and originating a trifle farther forward. Ventrals small, bases near 

 anal. Body cavity hardly half of the length to the caudal. 



Body and head are both more compressed in this genus than in Rivulus ; 

 the body is deeper in the forward half and rather more slender in the caudal 

 section ; the fin rays are more numerous, and the base of the dorsal is longer. 

 Compared with Pterolebias the body is deeper forward and has not the sharp 

 edge between ventrals and caudal. The head also is more compressed, the 

 snout longer, and the mouth more nearly horizontal. Four species have 

 been described from La Plata river, and one from Pernambuco ; of the five it 

 does not appear that more than three are valid. 



Cheek, preopercular, scales in six or more series ; Page 



LI. more than forty porosus 143 

 Cheek scales in two or three series ; 

 LI. less than thirty-five ; 



anal rays more than twenty-five Bellottii 144 



anal rays less than twenty-five maculatus 145 



Cynolebias porosus. 



Cynolebias porosns ^iemi.., 1876, Sb. Ak. Wien, LXXIV, extr. p. 125, pi. 10, fig. 3; Penig., 1891, 

 Ann. Mus. Civ. Gen., (2) X, 651 ; Eig., 1891, P. U. S. Mus., XIV, 65. 



Cynolebias elongatus St., 1881, Denk. Ak. Wien, XLIV, extr. p. 11; Eig., 1891, P. U. S. Mus., 

 XIV, 6i. 



B. 7; D. 17-18; A. 20 ; V. 5; P. 14; LI. ca. 45-48; Ltr. 21. 



Body compressed, depth at origin of dorsal nearly equal length of head, 

 equal three tenths of the body without the caudal, or little more than one 

 fourth of the total length. Back arched from head to hind end of dorsal. 

 Pedicel of caudal medium. Head compressed, crown flattened, cheeks covered 

 with scales, chin and throat naked. Eye small, lateral, hardly as long as 

 snout, two ninths of head, one half of forehead. Anterior nostril a short 

 tube. Mouth nearly horizontal; lower jaw longer, massive; chin steep; 



