1866.] MR. J. Y. JOHNSON ON TRACHICHTHYS DARWINII. 313 



not so far as the edge of the branchiostegal membrane. The height 

 of the opercle is not quite twice its width ; its surface is traversed 

 with strong roughened crests, radiating for the most part from a 

 point high up near the anterior margin. A higher and broader crest 

 crosses the upper part of the opercle, and projects beyond the border 

 as a strong but short spine. Above this transverse crest is another 

 series of smaller radiating crests. The edge of the opercle is irre- 

 gularly serrate or sinuous. The subopercle is narrow, and closely 

 applied to the lower and hinder edge of the opercle ;• its border is 

 entire, and its surface is set with numerous serrulate crests, except 

 at the upper part, where it is clothed with small scales. At the 

 lower end there is a spine projecting backwards and forming the 

 lower side of a sinus. The large interopercle is very rough°with 

 serrulate crests, and has a deep and wide sinus, which is covered by 

 the great spine of the preopercle. Between the anterior extremity 

 of the interopercle and the posterior angle of the lower jaw there 

 intervenes a stout membrane, in which are implanted some rough 

 bony plates, which seem at first sight as if they formed part of the 

 interopercle. 



All the branchiostegal rays, eight in number, are exposed, aud the 

 lowest three rays carry a serrulate crest. PseudobranchiEe are present. 



The hinder border of the suprascapula is serrulate, and its lower 

 part is obliquely crossed by a low crest, which terminates in a very 

 short spine. The scapula is narrowly elliptical, and wider above 

 than below ; its surface is striate, but it is destitute of a spine. The 

 strong humeral bone is broad above, and its surface is striate. 



The large imbricated striate bony plates (ten in the specimen) 

 forming & ventral keel extending from the root of the ventral fins to 

 the vent, increase in size from each end of the series to the middle ; 

 and each plate consists of a broad wing with spinulose edges, bent 

 down upon each side so as to embrace the abdomen, and of a central 

 elevated ridge, which projects backwards as a sharp spine. 



In front of the dorsal fin there is a row of glossy scales along the 

 ridge of the back from the occiput to the fin ; they have something 

 of the shape of, but are much smaller than, those of the ventral 

 keel; each has a short spine at the middle of the exposed margin. 

 The dorsal fin rises from a groove, is much longer than high, and 

 commences behind the root of the pectoral fins, but nearer to the 

 snout than to the base of the caudal fin. The spinous portion is a 

 little shorter than the soft part, and it falls in posteriorly as far as 

 the seventh spine, which is shorter than the eighth. The fourth is 

 the longest spine. The soft portion of the fin, which has all its rays 

 branched, is higher anteriorly than the spinous part, the third and 

 fourth rays being the longest. At each side of the base of both the 

 dorsal and anal fins there is a series of large rough scales, which are 

 somewhat trapezoidal in shape. 



The pectoral fins are inserted in the same horizontal line as the 

 lower ends of the maxillary, and considerably below the middle of 

 the height. They are ovato-lanceolate in shape, and they do not 

 reach nearly to the vent, not extending beyond the vertical of the 



Phoc. Zool. Soc— 1866, No. XXI. 



