191 



This species is distinguished from all its congeners by the long series of 

 strong sharp spines in the middle of the dorsal fin. On this account Messrs. 

 Goode and Bean (Oceanic Ichthyology, p. 518) separated it from the genus 

 Nemichthys and gave it the generic name Investigator, a course in which I am 

 unable to follow them. 



G-avialiceps, Wood-Mason MS., Alcock. 



Qavialiceps, Alcock, Ann. Mag. Nat. Hist., Dec. 1889, p. 460, and Nov. 1892, p. 364. 



Body exceedingly elongate, tail tapering. No scales. Lateral line indis- 

 tinct. Vent about a snout-length behind the gill-opening, near the anterior end 

 of the long abdominal cavity. 



Jaws produced to form a long slender bill, of which the upper part is 

 formed by the premaxilla? and vomer. Sharp teeth on the vomer, premaxilla?, 

 and mandibles. 



Eye small. Nostrils as in Nemichthys. Gill-openings wide, nearly conflu- 

 ent. Pectorals absent. Anal well developed. Dorsal ill-developed and begin- 

 ning a considerable distance behind the head. 



Gavialiceps differs from Nemichthys in having (1) no pectoral fins, (2) the 

 dorsal fin ill developed and beginning some way behind the head, (3) the eye 

 small, (4) the vent not quite so near the throat, and (5) the lateral line indistinct. 



152. Gavialiceps microps, Alcock. 



Qavialiceps microps, Alcock, Ann. Mag. Nat. Hist., Dec. 1889, p. 461 and Nov. 1892, p. 364. 



The head, of which rather more than two-fifths is formed by the long taper- 

 ino - snout is between a fifth and a sixth of the total length. The diameter of the 

 small subcutaneous eye is about one-eleventh the length of the post-orbital por- 

 tion of the head (measured to the gill-opening) and about a ninth the length of 

 the snout. 



The premaxillary teeth are arranged in a single row, and diminish in size 

 but increase in number from behind forwards, where they end in a narrow band 

 of minute asperities : the vomerine teeth posteriorly are long and sharp and are 

 disposed in a long, close-set, comb-like series ; anteriorly they form a fine rasp- 

 like band of minute asperities : in the mandible a row of large distant needle-like 

 teeth stands up from an uneven band of small denticles. Gill-openings close 

 together, wide. The scaleless integument is thin and deciduous and thickly en- 

 veloped in mucus ; no lateral line is apparent. The dorsal fin is feebly develop- 

 ed, and, indeed, hardly distinguishable, except in the posterior part of the body : 

 it begins about a head-length behind the head. The pectoral fin is represented 

 by an inconspicuous knob, without any rays. 



