XEY TO GENERA. — CYPRINID^E. 4 1 



Family: Cyprinid^E (The Minnows). 



Key to Genera. 



X (Dorsal fin long, with 2 or 3 spines, and 18 or 20 rays ; introduced species. 



A. Teeth in 3 rows, 1, 1, 3-3. 1, 1, all molar ; 4 barbels. — Cyprinus. 



AA. Teeth in 1 row, 4-4, molar, but compressed ; barbels wanting. — Carassius.) 



JI. Dorsal fin short, without developed spine. 



A. Air bladder surrounded by many convolutions of the very long alimentary 



canal. — Campostoma. 



AA. Air bladder above the alimentary canal, not surrounded by convolutions of the 

 intestine. 

 B. Alimentary canal more than twice the length of body ; teeth in 1 row > 

 peritoneum usually black. 

 C. Teeth 5-5 or 4-5 ; scales minute. — Chrosomus. 



CC. Teeth 4-4 ; scales larger. 



D. A small barbel present at base of maxillary ; color silvery. — 



Hybognathus. 

 DD. Barbel wanting; color olivaceous, little silvery. — Pimephales. 

 .BB. Alimentary canal less than twice the length of body; peritoneum usually 

 silvery. 

 F- Tower jaw normally formed, dentarv bones free from each other 

 except at the S3 f mphysis. 

 F. Teeth in main row 5-5 or 4-5. 



G. Abdomen rounded behind ventral fins, not compressed 

 into a scaleless ridge; anal basis >hort. 

 H. A minute barbel present on maxillary at a little 



distance above its base. — Semotilus. 



HH. Maxillary without barbel. 



I. Teeth in 2 rows, 2, 4-5, 2. — Leuciscus. 



II. Teeth in 1 row, 5-5. Mouth extremely small. — 



Opsopceodus. 

 GG. Abdomen compressed behind ventral fins into a sharp, 

 scaleless ridge; anal basis longer. — Abramis. 



TF. Teeth in main row 4-4. 



J. Maxillary without barbel. 



K. No cavernous lymph spaces visible in mandible, 

 sub-opercle and inter-opercle. 

 T- First (rudimentary) ray of dorsal detached 

 from the first developed ray and connected 

 to it by a membrane; a conspicuous black 

 spot at base of caudal and dorsal — Cliola. 

 Tie First (rudimentary) ray closely attached to 

 first developed ray. — Notropis. 



KK. Mandible, sub-opercle and inter-opercle, with con- 

 spicuous, externally visible, cavernous lymph 

 chambers. — Fricymba. 



JJ. Maxillary barbel present. 



M. Premaxillaries not protractile, connected to skin of 

 forehead in the median line without a cross 

 groove; teeth 2, 4-4, 2. Rhinichthys. 



MM. Premaxillaries protractile, a cross groove separat- 

 ing them from the skin of forehead in front; only 

 1 tooth in lesser row.— Hybopsis. 



XE. Tower jaw singularly formed, the dentary bones parallel and united 

 for their entire length ; a conspicuous, fleshy lobe on each side at 

 base. — Exoglossum. 



