SILURIDZ. 15 
tion®of the supraoccipital or interparietal bone into the head of the 
second interspinal. <A firm and immovable bridge is thus formed, 
which gives an uninterrupted passage from the dorsal fin to the snout. 
The silvery coloration is also a marked distinguishing feature. 
It is not generally true that the species of Jchthelurus reach a 
larger size than those of the other genera. Amiwrus nigricans and Pe- 
lodichthys olivaris far exceed in size any of the species of Ichtheelurus. 
ANALYSIS OF SPECIES.* 
*, Anal fin extremely elongate, its base about one-third the length of the body (without 
caudal); its rays 32 to 34 in number; eye small, wholly anterior, the middle of 
the head being entirely behind its posterior margin; head small,about 4} in 
length; depth 4 in adults to 54 in younger specimens; slope from dorsal to suout 
somewhat concave, especially in adults; pectoral spine 14 in head; skin thin; 
colorabrichtlysilvenyresessn tas store closet se classameee arcs | batSe SEE FURCATUS, 1. 
**, Anal fin shorter, 34 to 4 in length; its rays 24 to 30. 
t. Eve moderate-sized, anterior, the middle of the head being wholly behind it; anal 
rays 27 to 30; body comparatively stout and deep, compressed behind; the dorsal 
region elevated ; depth 34 to 4 in length; head pretty large, 4} to 44 in length, 
one-third longer than broad ; spines moderate, strong, little more than half-head ; 
profile from dorsal to snout more or less depressed or concave; skin rather thick ; 
COLOTS| PaO ea aa ces 8 ania mae see ee sepactere clamacia hissed) tewrepe lca als ROBUSTUS, 2 
tt. Eye large, placed Seely, the middle of the length of the head falling within 
the eye; anal rays 25 to 29; head moderate, about 4 in length; depth about 5; 
body more elongate and“less agey than in robustus, the head rather smaller, the eye 
larger, and the dorsal region less elevated ; pectoral and dorsal spines long, each 
aboutlyanileng bly of head! ais. 22 eascrsin ce siceeisccisie ae oases eae - PUNCTATUS, 3. 
1. LOATHALURUS FURCATUS, (Cuv. & Val.) Gill. 
Fork-tailed Channel Cat. 
(Figs. 1 and 2.) 
Pimelodus: furcatus, Cuv. & VAL. (1840), xv, 136.—De Kay (1842), Fishes N. Y. 187.— 
STORER (1846), Synopsis, 403. 
Ictalurus furcatus, GILL (1862), Proc. Bost. Soc. Nat. Hist. 43.—JorpDaNn (1876), 
Man. Vert. 300.—JoRDAN & COPELAND (1876), Check List, 159. 
Amiurus furcatus, GUNTHER (1864), Cat. Fishes, v, 103. 
Pimelodus afjinis, BAirD & GiRARD (1854), Proc. Acad. Nat. Sci. Phila. 26.—GirarRD 
(1859), Ich. U. S. and Mex. Bound. 32. 
Ictalurus affinis, GILL (1862), 1. c. 43.—JoRDAN & COPELAND, 1. c. 159. 
Amiurus afinis, GUNTHER (1865), 1. c. 103. 
Habitat.—Mississippi Valley to Texas. 
This species is not nearly so common nor so well known as the 
punctatus. I am unable to distinguish the type specimens of affinis 
from furcatus. 
*T. meridionalis is here omitted, the description not being sufficiently full to allow 
@ satisfactory contrast of its characters with those of I. robustus. 
