SYNOPSIS OF THE CYPRINID./E OF PENNSYLVANIA. 



365 



H. hsematurus, where the form of the mouth and the squamation are about the same ; 

 the dentition is an infallible distinction. I have examined large numbers of individuals 

 of both, from various parts of Michigan and Indiana. 



Several species not yet detected in our State are introduced for comparison. Our species 

 are distributed as follows : 



A. micropogon, 

 A. biguttatus, 

 A. dissimilis, 



Susquehanna. 



Ohio, Lake, and Susquehanna. 



Ohio. 



I. Mouth terminal; teeth 4.0—0.4 or 4.1—1.4; scales larger, radii stronger; isthmus medium. 



Head short convex, end maxillary opposite eye, which enters length head 3i times; caudal peduncle slender; 

 yellowish, a dark lateral and median dorsal band. microi'OGON. 



Head elongate, with muzzle slightly projecting, 4J times in length; outline arched from end muzzle, depth 

 equal head; scales I 40 ; teeth 1.4 — 4.1 ; dark band on muzzle and spot at base of tail. stigmaticus.* 



Head obtuse, dorsal outline flat; height 4§ length ; lateral line nearly straight; eye 5J times in head; scales 

 I 41 ; teeth 1.4 — 4.1 or 0; caudal peduncle thick; olive above, yellowish below; operculum rounded above. 



CYOLOTIS.f 



Head elongate, acuminate, dorsal outline flat, depth 4f length, eye 5— 5 J times in head; caudal peduncle short; 

 scales | 40; teeth 4 — 4; operculum angulated above. isiguttatus. 



II. Mouth slightly inferior; teeth 0.4—4.0; scales larger; radii stronger; isthmus medium. 



Slender, eye largo, head one-flfth length ; scales 1. 1. 49 ; dorsal fin larger than anal ; a lead-blue lateral band. 



DISSIMILIS. 



Slender, eye largo, twice in length of muzzle; bead one-fourth length ; scales 1. 1. 70, dorsal smaller than anal. 



OATAEACTiE.J 



III. Mouth terminal, small ; teeth 2.4—4.2 ; scales larger, concentric lines stronger; isthmus narrow. 



Head one-fifth total length, depth body equal; eye one-fourth length of head; muzzle obtuse; scales 10-12— 

 61-5—7-9; head and above blackish, a plumbeous band above lateral line, white below. prostiiemius.S 



* Ceratichthyi stigmaticus, Cope, Proc. A. N. Sci., Phila., 1864, 278, from Michigan. 



f Ceratichthys cyclotis, Cope, /. c, p. 278, from Michigan and Kansas. 



;|; Gobio cataractas, Cuv. Val., from Niagara. The pharyngeal teeth of this species arc not described, but the 

 inference from C. V., is that they are more as in Gobio. 



§ Ceratichthys prosthemius, in. sp. nov. 



This is a fish of the average size of Semotilus corporalis, but much more slender form; 

 the outline is fusiform, the head being small and the muzzle broad and abruptly descending. 

 Baok compressed medially, first dorsal ray medial between end muzzle and origin caudal, 

 considerably longer than first anal, its base longer than base of anal, ventrals opposite first 

 dorsal ray, not reaching vent. End of maxillary not extending to opposite orbit; nares 

 equally distant from each other and promaxillary margin. 



