Jordan and Evermann. Fishes of North America. 2569 



genus and its allies differ from Macrourus in the important character of 

 the structure of the first gill arch, (rpaxvt, rough; pvy%os, snout; 

 hence properly, but not originally, spelled Track yrrhynchus.) 



2943. TRACHYHINCUS HELOLEPIS, Gilbert. 



Head 3| in total; depth?; eye large, 4 in head, = interorhital width ; 

 snout 2^, its greatest width If in its length. D. 11. Snout depressed, flat, 

 narrowly triangular, tapering to a sharp point, its lateral ridges con- 

 tinuous backward over suborbital chain and across cheek. Interorbital 

 space wide and flat. Ethmoidal ridge not prominent. Mouth wholly 

 inferior, U-shaped, overpassed by the snout by a distance contained 3 in 

 head. Barbel slender, short, less than } diameter of orbit. Teeth finely 

 villiform, in very broad bands in each jaw, none of them enlarged. Max- 

 illary reaching to or almost to vertical from hinder margin of orbit, 3 in 

 head. Opercle very small, triangular, its length behind preopercular 

 margin scarcely more than \ diameter of orbit; outer gill arch not adnate 

 to the opercle, its lower limb with 17 short gill rakers, which are not 

 tubercular. Distance of dorsal fin from nape 3| in head, the 2 dorsal fins 

 closely approximated; second dorsal ray not spine-like, soft and flexible, 

 and not longer than the succeeding rays, its length the diameter of orbit. 

 Vent located immediately in front of origin of anal fin, its distance from 

 ventrals 1| in head. Ventrals short, inserted well in advance of base of 

 pectorals, the outer ray little produced, its length H in diameter of orbit. 

 Scales all with their margins embedded, and therefore appearing non- 

 imbricated, the central portion of each projecting, tubercle-like, and 

 bearing a single strong central spine, with sometimes 2 or 3 smaller ones; 

 belly and breast sometimes covered with much smaller scales similarly 

 armed ; no naked area between bases of ventrals ; enlarged plates along 

 bases of dorsals and anal bearing each a strong compressed backwardly- 

 curved spine, usually without distinct serrations; from the base of the 

 central spine radiate lines of short spinous points ; dorsal series of plates 

 continued forward to the nape, the predorsal portion of the included 

 groove covered with scales; ventral series scarcely extending beyond 

 vent, but extending farther posteriorly than do the dorsal plates ; scales 

 on top of head with a median serrated ridge; temporal fossai small but 

 evident, naked. Color apparently dark brown; gill cavity and perito- 

 neum black. Pacific Ocean, off the coast of Central America, in deep 

 water. Only the type known, a specimen 18 inches long. (^Ao, tubercle; 

 A.8Jtig, scale.) 



Trachyrhynchus hclolepis, GILBERT, Proc. TJ. S. Nat. Mus. 1891, 562, Pacific Coast of Cen- 

 tral America in deep water. (Type, No. 48205.) 



998. MALACOCEPHALUS, Gunther. 



Malacocephalus, GUNTHER, Cat. Fish. Brit. Mus., iv, 396, 1862 (Icevis). 



Intermaxillary teeth biserial, mandibulary teeth uniserial. Mouth lat- 

 eral; snouth short, obtuse. Head without prominent ridges, with wide 

 muciferous cavities. Dorsal fin over origin of pectorals, its longest spine 

 3030 84 



