650 ON A TRACHYPTERirS FROM N.S.W., 



not extend backwards beyond the anterior border of the eye; the 

 mandibular rami are extraordinarily deej^, the hinder and lower 

 borders being of equal length. The mouth is situated on a level 

 with the inferior border of the eye. 



Teeth : — The dentition is imperfect, the only teeth now remain- 

 ing being a single very strong sharp acutely-conical one on each 

 ramus of the upper jaw, behind which is a much smaller but 

 similarly shaped tooth; no teeth can be detected on the lower 

 jaw. 



Eye .-—The eye is very large and round, situated in the middle 

 of the ujiper surface of the head, its longitudinal diameter being 

 2i in the length of the head. 



Branchial apparatus : — All the opercles are ornamented with 

 radiating striae similar to those of the maxillary, as also is the 

 articular bone; the opercle is of moderate size, and appears to 

 have been produced backwards well beyond the scapular arch; it 

 is bordered below by the enlarged and band-shaped interopercle,, 

 which overlaps and almost entirely conceals the small aborted 

 subopercle; the preopercle is crescentic and with the interopercle 

 extends forwards to beyond the vertical from the anterior border 

 of the eye, leaving below the eye a triangular naked space bordered 

 by the hinder margin of the dentary and the preopercle; the 

 branchiostegal rays are six in number, and there are nine gill- 

 rakers — so far as I can ascertain without injuring the specimen 

 — on the lower branch of the anterior arch; they are short, stout, 

 and subclaviform; narrow at the base, compressed and knife-like 

 above, the second (from the articulation) the longest, about | of 

 the diameter of the eye. 



The fias. — Dorsal fin: — The anterior detached (or semi- 

 detached) portion of the dorsal fin originates a little in advance 

 of the posterior border of the eye and but a short distance behind 

 the termination of the premaxillary groove; it consists of five 

 rays, all of which are broken off at a short distance above the 

 base; the portion of the first ray which is still in sitii is armed 

 anteriorly with curved spinules, as also is that of the second, Ijut 



