PHILIPPINE MACROUROID FISHES — GILBERT AND HUBBS. 521 



7c\ Striations behind ventral fins much finer than those above 



ventrals or on isthmus ; form more slender italicus. 



7c 2 . Striations behind ventral fins not finer than those above 



ventrals or on the isthmus; form more robust 



cavemosus. 



f. Barbel minute or obsolete; no striated areas directly below 



pectoral bases nor in front of ventral bases; compared 



with cavemosus, the ventral lens-like bodies are smaller, the 



color is darker, and the bands of teeth are narrower 



antraeus. 1 

 i 2 . Snout about as long as the interorbital width, projecting beyond 

 mouth, pointed ; barbel wholly absent, or rudimentary. 

 I 1 . Color lighter, grayish along bands of teeth in jaws. 



to 1 . Ventral rays usually 11, sometimes 12 lethonemus. 



to 2 . Ventral rays usually 12, sometimes 11 or 13 nascens. 



f. Color darker, black along bands of teeth in jaws; ventral 



rays 13 to 15 striatulus. 2 



h 3 . Eye 3£ in head, f interorbital width; snout f eye; barbel dis- 

 tinctly developed; ventral rays 10 to 12 (readily separable on 

 account of its small orbit from H. italicus and H. cavemosus, 

 the only species in the subgenus with which it agrees in the 

 number of ventral rays and the development of the bar- 

 bel) heterolepis. 



A : . Body deeper ; sensory canals of head excessively developed, as in the typical 

 subgenus of Bathygadus; bony septa of skull exceedingly thin and 

 papery ; eye small, 4 to 5 in head; color chiefly blackish. 



PAPYROCEPHALUS. 



a 1 . Barbel present, very small. 



6*. Ventral rays 7 barbatulus. 



b 2 . Ventral rays 11 papyraceus. 



a". Barbel absent ; ventral rays 13 or 14 aterrimus. 



Hymenogadus, new subgenus. 



Type-species. — Hymenocephalus gracilis, new species. 



This subgenus is erected to include two closely related species — 

 the type-species and H. tenuis 2 — which we have recently described 

 from the Hawaiian Islands. The two species are closely related, and 

 differ strikingly from all other known species in the denticulation of 

 the dorsal spine, in the reduced gill-rakers, and in the cylindrical 

 form of the head. Their reference to Hymenocephalus is made be- 

 cause of their agreement with the other species of the genus in the 

 possession of certain diagnostic characters conservatively retained 

 throughout the group. Among these characters the most prominent 

 are: the forward extension of the branchial aperture; 3 the compara- 

 tively wide slit before the first gill-arch; the " striation " of the 

 abdominal region; the presence of two lens-like bodies in constant 



i Specimens of this Hawaiian species from Albatross station 3467 have never been 

 recorded. 



2 Gilbert and Hubbs, Proc. U. S. Nat. Mus., vol. 54, 1917, p. 173. 



3 In this character Hymenocephalus is approached by two other genera, Malacocephalus 

 and Ventrifossa. 



