36 



MONOGEAPH OF THE FRESH WATER 



III. 



/Body fusiform, 

 elongated. 



COTTI^ 



/With five rays/ 

 to ventral fins. 



^ Body stout and 

 short. 



•Body fusiform 

 and slender. 



/Origin of anal fin opposite to third ray of 

 second dorsal. Pectorals shorter than 

 the head. Vent placed midway between 

 snout and tip of caudal fin. 



lOrigin of anal fin opposite to sixth ray of 

 second dorsal. Pectorals of same length 

 as head. Vent nearer to snout than 

 to base of caudal fin. 



C. RiCHARDSONll. 



C. COGNATUS. 



With four 

 rays only to( 

 ventral fins. 



Body cylindri- 

 cal, or subcy- 

 lindrical and ^ 

 stout. 



Upper rays of pectorals branched; their tip 

 extending to anterior margin of second 

 dorsal. Insertion of.ventrals in advance 

 of first dorsal. 



C. WiLSONII. 



' First dorsal very low. Tip of pectorals ex- 

 tending beyond the anterior margin of 

 anal. Insertion of ventrals opposite to 

 the first ray of anterior dorsal. 



/A second very minute preoperoular spine. 

 Origin of anal opposite to third ray of 

 second dorsal. Tip of pectorals extend- 

 ing beyond the anterior margin of the 

 second dorsal and anal. Insertion of 

 ventrals near the lower edge of pectorals 

 in advance of anterior dorsal fin. 



(A second and third, exceedingly minute, 

 preoperoular spines. Origin of anal op- 

 posite to fourth ray of second dorsal. 

 Tip of pectorals not reaching the anal fin. 

 Insertion of ventrals even with the lower 

 edge of pectorals in advance of the first 

 dorsal fin. 



/Base of pectorals crescentic; their tip ex- 

 tending beyond the fifth ray of second 

 dorsal and third of anal fins. Insertion 

 of ventrals in advance of the anterior 

 dorsal, near the lower edge of pectorals. 



C. Bairdii. 



C. Alvoedii. 



C. MERIDIONAT/IS. 



C. BOLEOIDES. 



lA second minute preoperoular spine. Tip 

 of pectorals not reaching the anterior 

 margin of second dorsal. Base of pec- 

 torals crescentic. Dorsal fins separated 

 by a free space. 



fBase of pectorals crescentic; their tip ex- 

 tending beyond the fourth ray of second 

 dorsal and first of anal fin. Insertion of 

 ventrals under the pectorals and in ad- 

 vance of anterior dorsal. 



.Base of pectorals slightly curved ; their tip 

 not reaching the anterior margin of second 

 dorsal. Insertion of ventrals in advance 

 of anterior dorsal and under the middle 

 of pectorals. 



'Base of pectorals crescentic; their tip not 

 reaching the anal fin. Insertion of ven- 

 trals under the upper edge of pectorals. 



Base of pectorals straight; their tip not 

 reaching the anterior margin of anal. 

 Insertion of ventrals behind the base of 

 pectorals, and in advance of the anterior 

 dorsal. 



C. FORMOSUS. 



C. GRACILIS. 



C. Franklinii. 



C. GOBIOIDES. 



C. VISCOSUS. 



J Head subtuberculous; region behind the 

 f eyes and lateral line, rough. 



C. Fabricii. 



