FORK-TAILED CHANNEL CAT. 785 



Head conical In profile, compressed, and with the sides sloping downward and out- 

 ward. The supraoocipital bone is prolonged backward, and its emarginated apex re- 

 ceives the aonminate anterior point of the second interspinal. The skull is covered by 

 a thin tense skin, through which the sculpture of the bones is apparent f eyes large 

 and almost entirely lateral ; mouth small, transverse, and terminal ; the upper jaw 

 protrudes beyond the lower ; teeth subulate and aggregated into a short, laterally trun- 

 cated band on each jaw. Branchiostegal rays 8 or 9 ; dorsal fin situated over the inter- 

 val between the pectoral and ventral fins, higher than long, with one long spine and 

 usually six articulated rays ; adipose fin pedunculated over the posterior portion of the 

 anal ; anal fin long, and provided with from 35 to 35 rays; it commences near the anus ; 

 ventral fins each with one simple and seven branched rays ; pectoral fins each with a 

 stout spine, retrorse-serrate within, and about nine branched rays The serrte of the 

 pectoral spines vary with age and circumstances, and do not in this genus give good 

 specific characters. Caudal fin elongated and deeply forked, with the lobes equal and 

 pointed. 



The genus IchthcBlurua is at once recognized by the forked caudal fin, its silvery or 

 olivaceous colors, and by its compressed, elongated, and slender body which gives 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 

 covered by so thick a skin ; the mouth is proportionally much smaller. But the only 

 invariable generic distinction resides in the mode of insertion of the supraoocipital 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 fiu to the 

 snout. The silvery coloration is also a marked distinguishing feature. 



It is not generally true that the species of Ichthcelurus reach a larger size than those 

 of the other genera. Amiurus nigricans and Pelodichihys olivaris far exceed in size any of 

 the species of Ichthcelurus. 



12. IcHTHiELURWs FOECATUS (Cuv. and Val.) Gill. 



Fork-tailed Channel Cat. 



Pimelodus furcatus, Cuv. and Val. (1840), Hist. Nat. des Poiss., xv, 136. 

 IchlJialvrus furcatus, Gill (1861), Proo. Bost. Soc. Nat. Hist., 43. 

 Amiurus Jurcatus, Gunthbr (1864), Cat. Fish. Brit. Mus., v, 103. 



Ichthcelurus furcatus, Jordan, Bull, U. S. Nat. Mus., x, 75; Man. Vert., Ed. 2d, 1878, 328. 

 Pimelodus affinis, Baied and Gikard (1854), Proo. Ac. Nat. Sci., Phila., 26.— Gieard (1859), 

 U. S. Mex. Bound., loh., 33. 



Description. — Body very slender ; head slender, the eye small, wholly anterior, its pos- 

 terior margin being in front of the middle of the head; slope from snout to dorsal fin 

 more or less concave ; skin thin ; coloration brightly silvery ; anal fin extremely long, 

 with 32 to 34 rays ;* its base forming one-third of the length of the body and head ; 

 head 4J in length ; depth, 4 in adult, EJ in young ; pectoral spine li in head ; length 1 

 to 2 feet. 



Habitat, Ohio Valley to Texas, in the larger streams ; not common. 



* In this family the rudimentary rays at the beginning of the anal are always in- 

 cluded in the enumeration. 



50 



