90 



Both head and body are covered with small deciduous cycloid scales — so 

 deciduous on the head that except in very well preserved specimens that part 

 may be thought to be naked. 



Lateral line indistinguishable. 



Snout hardly overhanging the lower jaw, depressed ; without barbels. 

 Mouth very wide. Villiform teeth in bands on the jaws and palatines ; few and 

 scattered, deciduous or absent, on the vomer. 



Eye of moderate size. 



Gill-openings wide : gill covers armed with spines. Eight branchiostegals. 

 Pseudobranchiaa rudimentary or absent. Preoperculum expanded much as in 

 Bassozetus. The gill-rakers on the outer side of the first branchial arch are long 

 and most curiously compound. 



Dorsal and anal fins confluent with the caudal. The ventrals arise close 

 together at the clavicular symphysis : each consists of a single filament, which 

 may be bifid at its extremity. 



Air-bladder small. Pyloric caeca absent or quite rudimentary. 



This genus is very closely related to Bassozetus, from which it only differs 

 in the following particulars : — 



(1) the bones of the head are firmer and are armed with numerous spines : 



(2) the teeth on the vomer are few and scattered, or are entirely wanting. 



Alcochia G-oode and Bean, Oceanic Ichthyology, p. 329, probably should be 

 united with Dermatorus. 



Key to the species of Dermatorus. 



I. Spines of the head rigid : diameter of eye about two-ninths the length 



of the head : some vomerine teeth present ... ... ... D. trichiurus. 



II. Spines of the head weak and flexible : diameter of eye a sixth or a 

 seventh the length of the head ; — 



1. Some vomerine teeth ... ... ... ... B. melanocephalus. 



2. No vomerine teeth ... ... ... ... B. melampeplus. 



69. Dermatorus trichiurus, Alcock. 



Dermatorus trichiurus, Alcock, Ann. Mag. Nat. Hiac, Oct. 1890, p. 298 : Illustrations of the Zoology op 



THE INVESTIGATOB, FlBHES, PL. I- FIG. 1. 



D. 160 + x. A. 140 + 0. P. circ. 16. V. 1. (split at the end). 



Head between a sixth and a seventh the total length : greatest height of the 

 body equal to the length of the head behind the posterior border of the pupil. 



Two small preorbital spines. A s'rong recurved spine at the anterior angle 

 of the orbit from which two irregular series of spines pass backwards to the 



