GREAT FORK-TAILED CAT. 789 
the pectorals and ventrals, higher than long, with a pungent spinous ray dentate behind, 
and about six branched rays; adipose fin short, inserted over the posterior half of the 
anal; anal fin of moderate length, with from fifteen to twenty-six rays, the usual num- 
ber being twenty or twenty-one; caudal fin short, usually truncate when spread open, 
slightly emarginate when not expanded,—in species related to Ichthelurus more or less 
deeply forked, in some other species rounded; when the caudal fin is forked the lobes 
are usually unequal; ventrals each with one simple and seven branched rays; pectoral 
fins each with a stout spine, which is commonly retrorse-serrate behind, these serra vary 
much with age and circumstances, and do not appear in this genus to furnish good SD 
cific characters; lateral line usually incomplete. 
This genus includes our common Eastern American Catfishes, and is readily recognized 
by the broad head covered by a thick skin, the freetermination of the posterior process 
_of the supraoccipital bone, the compressed body, and by the free adipose fin. ; 
This genus, althongh undoubtedly a very natural one, israther hard to defing Cer- 
tain species (lupus, niveiventris, nigricans) have real affinities with the species of Ich- 
thelurus, having, like them, the body elongate, the head rather narrow, the ana! long, 
the caudal forked, and the coloration pale. The absence of the connection between 
the supracccipital and the interspinal is the only technical character by which Amiurus 
may be distinguished from Ichthelurus. 
ANALYSIS OF SPECIES OF AMIURUS. 
* Caudal fin forked. 6 6 5 6 . 6 . : : NIGRICANS. 15. 
** Caudal fin rounded, or slightly emarginate. 
a, Anal rays 24 to 26. ; : 6 : 6 6 5 : ‘ NATALIS. 16. 
aa. . Anal rays 18 to 22. 
b. Lower jaw longer than upper. 6 6 6 6 6 . VULGARIS. 17. 
bb. Lower jaw not longer than upper. 
c. Coloration mottled or variegated; adipose fin large. . MARMORATUS. 18. 
ec, Coloration nearly plain. 
d, Head moderately broad, with a nearly even slope from the tip of the 
snout to the elevated base of the dorsal fin. 
e. Body elongate; anal rays 20 to 22. . 5 ‘ 6 . CATUS. 19. 
ee. Body short and deep; anal rays 18 to 20. . é 6 . MELAS, 20. 
dd. Head very broad ; an angle at occiput; anal small, usually with 19 rays. 
XANTHOCEPHALUS. 21. 
15, AMIURUS NIGRICANS (LeSueur) Gill. 
Great Fork-tailed Cat; Mississippi Cat; Florida Cat; 
Great Catfish of the Lakes. 
Pimelodus nigricans, LESUEUR (1819), Memoires du Museum d’Hist. Nat., v, 153.—Cuv. 
and VaL. (1840), xv, 133.—DEKay (1842), Fishes N. Y., 180.—STorER (1846), 
Synopsis, 403.—*‘ HyrTL (1859), Denkschrift Akad. Wiss. Wien, xvi, 16.” 
Amiurus nigricans, GILL (1862), Proc. Bost. Soc. Nat. Hist., 44—JorDAN (1876), Man. 
Vert. 318.—JORDAN and CopELAND (1876), Check List, 159 (not of GUNTHER (1864), 
nor of CopE (1870), equal to A. cwnosus).— JORDAN (1877), Bull. U. S. Nat. Mus., x, 83; 
(1878), Man. Vert., sec. ed., 329. 
Silurus (Pimelodus) nigrescens, RICHARDSON (1836), Fauna Bor.-Am., Fishes, 134. 
Pimelodus sp. incog., THOMPSON, (1842), History Vermont, 139. 
