NATURAL SCIENCES OP PHILADELPHIA. 283 



One specimen from Grosse Isle, Detroit River. 



Though differing in the development of the lateral line, this species stands 

 near Pimephales in the character of the separation of the bony dorsal ray from 

 the first cartilaginous by a membrane, (erroneously alluded to by some as a 

 peculiar ray,) and in the arrangement of the tubercles on the front. Of the 

 latter, there are two rows crossing the front of the muzzle ; the inferior of six, 

 of two on each side on the premaxillary border, and the outer near the eye ; 

 the superior of five, one on the middle line. A third row of four is on the 

 border of the superior plane, one behind each pair of nares, and one on each 

 side the middle line of the muzzle. 



Hybognathus stramineus. 



This genus embraces the described species argyritis. evansi, nu- 

 chalis, nitidus, regius and probably g a r d o n e u s (C. V. ), to which 

 are added here three others. 



In the present species, the dorsal is situated nearer the end of the muzzle 

 than to the base of the caudal, and its height is much less than half the dis- 

 tance from the base of its first ray to the same point ; the head enters the 

 length to the caudal a little over four times, being relatively longer than in the 

 species described by Agassiz and Girard, while the eye, entering the length of 

 the head but three times, is relatively larger. The depth enters the length 

 4^ times. Scales f 36 ; in evansi* f 40. Ventral fins do not extend to the 

 vent. The dorsal outline rises gently to the base of the dorsal ; the profile 

 descends abruptly at the end of the muzzle, which is prolonged in front of the 

 orbit about three-fourths the longest diameter of the latter. Superior border 

 of operculum usually shorter than the posterior. Pharyngeal teeth 4 4. 



The general form is stout, and the head broad ; caudal not deeply forked. 

 Fin rays -D. 1. 8. C. 19. A. 7. V. 8. P. short, 13. Length about three 

 inches. Color brownish straw color ; sides and below silvery, the former 

 most brightly. No dorsal line ; a faint line on posterior part of lateral line, 

 and a small spot at base of tail. 



Many specimens from Grosse Isle, Detroit River. 



Hybognathus v o 1 u c e 1 1 u s.f 



A species distinguished by its depressed elongate head and elongate fins, 

 especially the dorsal. The latter is as far from the end of the muzzle as from 



but differs in the much more posterior position of the fins. In this, the anterior base of dorsal is 

 equidistant between end of muzzle and base of tail: in the antica much behind the median 

 point; the ventrals are much nearer the caudal than the chin; in the formosa, the reverse is 

 the case. Scales - 1 % 50. Head in adults a trifle more than one-fourth total length; eye one-fifth 

 length of head. Maxillary not reaching line of margin of orbit; mouth oblique. Profile long, 

 flat, descending; dorsal outline arched. Body of medium proportions, shortened behind; caudal 

 Peduncle short, thick, Fins, D. 1 7 A; C. 19, short, emargination shallow; A. 18; V.9; P. 16 



Sides of head and edges of scales punctulate; general tint above purplish-slate; below, with 

 sub- and inter-operculum, yellow. Largest specimen five inches long. In some small specimens 

 the eye is only one-fourth the length of the head. To the allied genus Lavinia belongs most pro- 

 bably the Leuciscus boscii of Cuv. et Val., from Carolina. The same genus occurs in Lake 

 Ponchartrain. 



* Brought by Hammond from the Upper Platte. 



t Hybognathus procne has been sent me by my friend, Jacob Staaffer, as an inhabitant of 

 the Conestoga, tributary of the Susquehanna. A small silvery fish, with compiessed body and 

 elongate caudal peduncle. Head enters total length 4% times ; diameter of eye into head 2% or 

 three times. Depth into length five or a little more times. From anterior base of dorsal to base 

 of caudal longer than from former to end of muzzle; dorsal high, anterior rays equal % from 

 their base to base of caudal. Scales j? 31. Tail entering total length 5i%. times, deeply forked ; forks 

 acute. Obliquity of mouth slight. Operculum higher than long; its infero-posterior border very 

 oblique, long. Teeth R. 5 4 L. Length 2 - 5 inches. 



Top of head, a narrow dorsal band, and the borders of the upper scales blackish; belly and 

 ides of body and head silvery, along the middle line with blue reflections and black punctulations, 

 the latter collected into a streak on the lateral line. Belly yellowish. 



1864.] 



