390 



SYNOPSIS OF THE CYPRINIDiE OF PENNSYLVANIA. 



three-fourths height of first ray, and two-thirds base of anal, its superior outline straight; first (soft) anal ray just 

 equal base of anal; exterior outline of latter concave. Pectorals extend two-thirds the distance to vcntrals, and 

 latter to vent. Rays D. 1. 7], A. 2, 14. V. 9, P. 16. Twenty rows of scales between isthmus and ventral fins. 



The upper surface of the head in back are in this species usually blackish, and the rest of the body with green- 

 ish, brassy, or golden lustre, the latter always on specimens from sluggish and muddy streams. 



This Stilbc rarely exceeds seven inches in length. In a specimen five and five-sixteenths 

 inches long, the caudal fin measures one inch, caudal peduncle to last anal ray .75 ; depth 

 at latter point nine-sixteenths ; depth at first dorsal ray one and three-eighths ; at middle 

 of pectoral 1.25; at occiput .875; length base of anal thir teen-sixteenths inch. 



This species is called minnow or shiner, and inhabits all the waters of our State. In 

 our rapid rivulets it is rarely seen of large size, and chiefly seeks the " cut offs " and ditches 

 which produce Anacharis and Nuphar (Splatterdocks). It is properly a fish of the dams 

 and ditches, and the sluggish streams near the coast, where it is extremely abundant. In 

 the ditches near Philadelphia a mischievous mode of taking it, practised by boys, is to 

 feed them with dough mixed with ground Cocculus Indicus. 



It is abundant throughout New England and the West, and has been brought from Lake 

 Whittlesey, Minnesota, by Dr. J. II. Slack, of this city. I have not been able to distin- 

 guish a S. compressa among our numerous specimens from Indiana, Michigan, etc. 



CHROSOMUS, Rafinesque. 

 Ichthyologia Ohiensis, 47, Agassiz, 1. c, 225. 



Pharyngeal teeth with extensive masticatory surface, 4-5 or 5-5, no outer row ; scales 

 very small, largely exposed, lateral line very short or none. Basis of anal fin short, dor- 

 sal above the space between ventrals and anal. Mouth small terminal; isthmus narrow. 



Prof. Agassiz, who characterized this genus first, affirms the teeth of the C. crythrogas- 

 ter to be arranged 5-5 ; in nine specimens, however, I find but two with this arrangement, 

 and seven 4-5 ; the number is 5-5 in the C. eos. In his paper on fishes from the Tennes- 

 see River, Prof. A. identifies a species with the former, which he says has continuous lat- 

 eral line ; this is perhaps a species of another genus. 



Two species only are known, and both occur in Pennsylvania. 



Mouth reaching opposite orbit ; teeth 4 — 5. 



Scales longitudinal rows 34 — 5; two dark bands separate 'on caudal peduncle; back unicolor; usually a lateral 



line. ERYTHKOGASTER. 



Mouth not reaching line of orbit ; teeth 5 — 5. 



Scales longitudinal rows 23; dark lines united on caudal peduncle; back spotted; no lateral line. 



EOS. 



