74 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY—II. 
Genus ICHTH AXLURUS,* (Rajfinesque) Guill. 
Ictalurus, RAFINESQUE (1820), Ichthyologia Ohiensis, 61. 
Elliops, RAFINESQUE (1820), Ichthyologia Ohiensis, 62. 
Synechoglanis, GiLu (1859), Annals Lyc. Nat. fist. Wil, 39. 
Ictalurus, GILL (1862), Proc. Boston Soc. Nat. Hist. 41. 
Ichthelurus, Corr (1869), Journ. Acad. Nat. Sci. Phila. 237.. 
ETYMOLOGY.—1y6ue, fish ; aAoupoc, cat. 
Typre.—Silurus punctatus, Rafinesque. 
Body elongated, slender, and much compressed. *The caudal peduncle 
is short but slender, and presents behind the anal an elongated ellipti- 
cal section. 
Head conical in profile, compressed, and with the sides sloping down- 
ward and outward. The supraoccipital bone is prolonged backward, and 
its emarginated apex receives the acuminate anterior point of the second 
interspinal. , The skull is covered by a thin tense skin, through which 
the sculpture of the bones is apparent. Eyes large and almost entirely lat- 
eral. Mouth small, transverse, and terminal. The upper jaw protrudes 
beyond the lower. Teeth subulate and aggregated into a short, laterally 
truncated band on each jaw. Branchiostegal rays, 8 or 9. Dorsal fin situ- 
ated over the interval between the pectoral and ventral fins, higher than 
long, with one long spine and usually six articulated rays. Adi- 
pose fin pedunculated over the posterior portion of the anal. Anal fin 
long, and provided with from 25 to 35 rays; it commences near the 
anus. Ventral fias each with one simple and seven branched rays. 
Pectoral fins each with a stout spine, retrorse-serrate within, and about 
nine branched rays. The serre of the pectoral spine vary with age 
and circumstances, and do not in this genus give good specific charac- 
ters. Caudal fin elongated and deeply forked, with the lobes equal and 
pointed. 
The genus Zchthelurus is at once recognized by the forked caudal fin, 
its silvery or olivaceous colors, and by its compressed, elongated, and 
slender body, which give to it a peculiarly graceful appearance, very 
unlike that of the stout, obese, and large-headed Amiuri. The head is 
smaller in proportion than in Amiurus, more compressed, and not cov- 
ered by so thick a skin; the mouth is proportionally much smaller. 
But the only invariable generic distinction resides in the mode of inser- 
*The characters of the genera of Siluride as here given are arranged from Prof, 
Gill’s Report on Ichthyology of Captain Simpson’s Explorations Across the Great Basin 
of Utah, pp. 416-431, with some additions and modifications. 
