NO. 2149. JAPANESE MACROUROID FISHES— GILBERT AND HUBB8. 141 



i'. Teeth biserial in jaws ; ridges of liead less prominent ; 

 the side of head little angulated at the suborbital 



ridge Abyssicola. 



e". Seven branchiostegal rays ; anus immediately before anal ; 

 midventral line with two lens-shaped bodies connected by ti 

 black ridge on wall of abdominal cavity, one immediately 

 before anus, the other in advance of ventrals; ventral re- 

 gions marked with striae, consisting of fine parallel lines 

 of alternating dark and silvery pigment; scales large and 

 thin, smooth or weakly spined ; more than 15 gill-rakers on 

 lower limb of second arch ; gill-membranes narrowly united, 

 the gill-opening extended forward ventrally ; species fragile, 

 less than a foot in length, and confined to tropical waters. 



Hymenocephalus. 

 e^ Seven branchiostegal rays ; anus remote from anal fin ; anus 

 preceded by a naked area ; no ventral stride ; scales small ; 

 gill-rakers fewer than 15 on lower limb of second arch; 

 gill-membranes broadly united, little extended forward ven- 

 trally ; species confined to tropical or subtropical waters. 

 j\ Premaxillary teeth biserial, mandibular teeth uni- 

 serial ; pyloric caeca very numerous and pro- 

 fusely branched; dorsal spine smooth and 



rounded Malacoccphalus. 



f. Premaxillary teeth in a band, mandibular teeth 

 varying from an irregular series to a band ; 

 pyloric caeca in moderate numbers, fewer than 

 100, not branched. 

 fc\ Bones of head firm, the sensory canals moder- 

 ately developed, the skull without high crests ; 

 form of body usually slender, the head not very 

 massive, the snout not exceedingly broad and 

 high, the tail not rapidly constricted from 

 trunk ; gill-cavity not restricted in size ; mar- 

 gin of preopercle not adnate ; barbel moderate 

 or long; lateral line pores, as in all genera 

 except SquaIogadt(s and Cetomirus, along a 

 well marked, continuous, superficial groove 

 (sometimes slightly interrupted) ; scales along 

 dorsal base not enlarged (except in Tracho- 

 nurus). 

 r. Scales everywhere well imbricate, their spinules 

 directed backward (except in Lionurus par- 

 vipes and L. cetonuropsis) ; dorsal spine 

 trenchant on anterior edge, and serrate 

 (serrations obsolescent in some forms) ; 

 small species, less than 15 inches long. 



»i\ Snout moderately produced Lionurus. 



ml Snout greatly produced, much as in Coelor- 



hynchns Mataeocephalus. 



P. Scales not imbricate, their spinules erect; 

 dorsal spine slender, smooth and rounded ; 

 snout moderately produced Trachonurua. 



