146 CONTEIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



CC. Teeth 5-5 or 4-5; pseudobrauclaiae present; dorsal fin inserted poste- 

 riorly. 

 D. Lateral lino complete ; rudimentary caudal rays numerous ; anal basis 



elongate.. Lavinia, 74. 

 DD. Lateral line incomplete ; anal basis short ; scales minute. 



Chrosomus, 75. 

 CCC. Teeth 4-4 ; dorsal fin nearly median. 



E. First (rudimentary) ray of dorsal slender, firmly attached to the first 



developed ray. 

 F. Scales very small, 85-90 in the lateral line, which is complete. 



ZOPHENDIIM, 76. 



FF. Scales larger, 35-60 in the lateral line. 



G. Lateral line complete Hybogxatiius, 77. 



GG. Lateral line incomiilete CoLiscus, 78. 



EE. First (rudimentary) ray of dorsal somewhat enlarged and blunt, 



connected by mem- 

 brane with the first de- 

 veloj)ed ray. 



H. Lateral line incomplete Pimephales, 79. 



HH. Lateral line complete Hyborhyxchus, 80. 



tt Intestinal canal short, less than twice the length of the body; teeth hooked, the 



grinding surface, ifpres- 

 J^ ' ent, narrow or rudimen- 



tary ; peritoneum usu- 

 ally pale. 

 $ Dentary bones parallel, united for their whole length. {Exo- 



glossiri(P.) 

 I. Premaxillaries not j)rotractile ; mandible with a conspicu- 

 ous fleshy lobe on each 

 side at base. 



EXOGLOSSUM, 81. 

 $5 Dentary bones arched, free from each other, except at 



the symphysis. {Leu- 

 cischiw.) 

 J. Abdomen behind ventral fins not comj>ressed to an edge, 



the scales passing over 

 it ; anal basis generally 

 short. 

 K. Teeth in the main row 4-4. 

 L. Maxillary without barbels. 

 M. Jaws each with a hardened bony sheath; first 

 ray of dorsal spine-like, 

 eounccted by membrane 

 with the first develojied 

 ray ; teeth 4-4. 



COCHLOGXATIIUS, 82. 



MM. Jaws without bony sheath. 

 N. Lower jaw with the lip thin or obsolete, not 

 developed as a fleshy 

 lobe on each side at 

 base. 

 C Mandible, interopercle, and suborbital not 

 cavernous. 

 P. Teeth 4-4, or 1, 4-4, 1 (1, 4-4, 2 in one spe- 

 cies). 



