2492 Bulletin 4.7, United States National Museum. 



anal fiu ; gill openings large, the membranes united anteriorly only, free 

 from the isthmus, as in Fierasfer. Pseudobranchht* wanting; no scales; 

 no lateral line ; no ventral fins. One genus with 4 known species, from the 

 North Pacific. 



951. LYCODAPUS, Gilbert. 



Lycodapus, GILBERT, Proc. TJ. S. Nat. Mus. 1890, 107 (fierasfer). 



Body naked. Ventrals wanting. Vertical fins united around the tail. 

 Gill openings wide, continued forward under the throat; the gill mem- 

 branes anteriorly narrowly united, loosely joined to the isthmus by a fold 

 of lax skin. Brauchiostegals 6. No pseudobranchise. Gills 4, a wide 

 slit behind inner arch. Gill rakers developed. Teeth present in jaws and 

 on vomer and palatines, none of them enlarged. Vent remote from the 

 throat. (Ly codes; aitovc,, footless.) 



a. Body slender, the depth 8 to 11 in length. 

 b. Head rather large, 4| to 5 in length. 



c. Head, body, and fins with very many mucous pores; dorsal rays 70 ; anal 60. 



DERMATINUS, 2863. 



cc. Head, body, and fins with very few mucous pores ; dorsal rays 82 ; anal 70. 



FIERASFER, 2864. 



bb. Head small, 7f in length ; gill openings not extending above base of pectorals. 



PARVICEPS, 2865. 

 aa. Body very slender, the depth about 15 in length; dorsal rays about 100. 



EXTENSUS, 2866. 



2863. LYCODAPUS DEBMATINUS, Gilbert. 



Head 4|; depth If in head; eye 5 in head; snout 4 ; maxillary 2. D. 70; 

 A. 60. Very similar to L. fierasfer, but the head, body and fins covered 

 with a thick loose skin which contains numerous pores, or openings for 

 the mucous canals. One series of these runs along middle of sides and 

 forms the lateral line ; it rises anteriorly above the gill opening, and is 

 continued forward on top of head, the two meeting between eyes; a 

 second series runs between eye and upper lip, and curves around on 

 middle of cheek, running upward to behind eye; one series runs along 

 a fold bordering mandible, 1 along preopercular margin, and 1 on 

 opercle. In L. fierasfer a few pores are visible on mandible, and 1 or 

 2 can frequently be made out on preopercular margins. The skin is very 

 thin and delicate, and the fin rays are very evident through the mem- 

 brane. The general proportions and the dentition of the type are essen tially 

 as in L. fierasfer, but the vomerine teeth are long and hooked backward. 

 Mandible heavier than in L. fierasfer. Origin of dorsal vertically above 

 axil of pectorals. Length of head and trunk total length. Teeth in 

 narrow bands in the jaws, a single series on vomer and palatines. Gill 

 membranes very narrowly joined below and free from the isthmus, as in 

 L. fierasfer. Pectorals much longer than in L. fierasfer. General color in 

 spirits light brownish yellow, made somewhat dusky by the pigment spots 

 in the skin ; body, and especially the fins, darker posteriorly. Aleutian 



