98 COXTRIBUTIOXS TO XORTH AMERICAN ICHTHYOLOGY IV. 
and below the caudal peduncle. Anal fin comparatively short, and rap- 
idly increasing in height for the first half of its length ; it has 12-20* rays. 
Ventrals roundt'd, and each has 1 simple and 8 branched rays. Pec- 
toral fins with a sliarp spine, of different forms in the different species. 
Y^ent at some distance in advance of the anal. Lateral line complete. 
In or above the axil of the pectoral fins is an orifice, which is the open- 
ing of the duct of a poison gland. “From it may frequently be drawn a 
solid gelatinous style ending in a tripod, each limb of which is dichoto- 
mously divided into short branches of regular length.” {Cope.) Size 
small. Fresh waters of the United States, {vmto:;, back; tail ; 
“means tail over the back”, Bajinesquc.) 
* Premaxillary band of teeth without lateral backward processes. (Sclnlbeodesi 
Bleekei’.) 
t Pectoral spine entire or grooved behind; adipose fin high and continuous with 
the caudal. 
a. Pectoral spine about half the length of the' head. 
81. ]V. gyriaiiis (Mitchill) Raf. 
Nearly uniform yellowish brown, sometimes blackish, without trans- 
verse blotches ; a narrow dark lateral streak and one or more dorsal 
ones. Body comparatively short and thick. Head large, its width 3^ 
4i in length of body; depth I-oi; head 3.^-4. Spines stout and rather 
long ; that of the pectoral fin straight, grooved behind, 2 J in the distance 
from snout to dorsal fin. Dorsal higher than long, inserted nearer anal 
than snout. Anal 13. Jaws nearly equal. Humeral process short. L. 
5 inches. New York, entire Mississippi Valley, and Upper Lake region ; 
rather common. 
{SiJuriis (jurinus Mitchill, Amer. Month. Mag. 1818, 322; Jordan, Bull. U. S. Nat. 
Mus. X, 102: liotiirus sialis Jordan, Bull. U. S. Nat. Miis. x, 102, 1877.) 
aa. Pectoral spine less than one-third the length of the head. 
85. IV. leptacaEStuiHS .Jordan. 
Color yellowish, somewhat mottled. Bodj' slender. Head small and 
narrow, longer than broad. Eye small. Upper jaw much projecting. 
Spines very short and slender; that of the dorsal not one- third the 
height of the fin; all less than one-third the length of the head; that 
of the pectoral retrorsely serrate on the outer edge, entire within. Head 
4A in body; its width 54; depth 5J; distance to dorsal 2|; pectoral spine 
* Throughout the account of this I'amily the rudimentary rays at the front of the 
anal are included in the emimeratiou. 
t Bleeker, Ichthyologiai Archipelagi Indici Prodromus, i, Siluri, 258: type Silurus 
gyrinus Mitch. {Schilbe, another genus of Siluridee ; eidog, like.) 
