328 Dr Handyside on the History of the Sternoptixince, 



apertures extend obliquely downwards underneath the lower jaw and 

 branchiostegous membrane, nearly as far as the mesian line, where the 

 narrow isthmus formed by the junction of the lingual bones to the sym- 

 physis of the humerals separates the two branchial openings from be- 

 low. The pre-opercule has its shaft flattened, its border finely denticu- 

 lated, and its angle armed with a strong spine projecting downwards and 

 forwards. The sub-opercule is in form an incurvated cone, having its 

 rounded base below, its concave thick margin in front, its outer surface 

 scabrous, and studded with polj'gonal cells, its convex posterior border 

 nnich attenuated, while superiorly it is acuminated. 



Spines. [2 Pre-opercular, 2 humeral, 2 ventral, and 1 dorsal.] Be- 

 sides the spine of the pre-opercule already described, there is behind the 

 trochlea of the humerus a small thick spine curving downwards and for- 

 wards, and overlapping the ulna and radius ; and below the symphysis 

 and isthmus of the ossa humeri, which are remarkably elongated at an 

 acute angle, there exists a sharp spine, which terminates each bone, and 

 projects downwards at a point midway between the centre of the mouth 

 and the ventral fins. A fourth strong spine curves downwards and for- 

 wards from the extremity of the pelvic bones on each side, and imme- 

 diately in front of the ventral fin ; and, lastly, in front of the first dorsal 

 ray there rises up obliquely backwards from the first interspinal bone an 

 extremely strong, scaly, or membranous moveable spine, thick and grooved 

 behind, but finely denticulated on its anterior margin. 



Fins. The dorsal fin is short, and has from eight to ten soft rays, bifid 

 at their extremities. The pectoral fins are small, and multi-radiated. 

 They present respectively tlie same number of rays as the dorsal, the su- 

 perior ray being double the length of the inferior, and the intermediate 

 rays varj' in length proportionally. The ventral fins possess each, be- 

 sides the spine, from five to seven very slender rays. They are placed 

 about the middle of the trunk, opposite to the dorsal fin, and imme- 

 diatelj' in front of the anus. The anal fin is shallow, with distant rays, 

 and is nearly longitudinal {i. e. extends a considerable way from the vent 

 towards the tail). It consists of thirteen distinct soft rays, each bifur- 

 cated at its extremity-. The caudal fin is forked, and has from thirty-six 

 to forty rays. 



Surface. The surface of the body of the Sternoptix is naked (or de- 

 void of scales). It is covered with a dark coloured translucent mucus or 

 epithelion. 



CoLouii. The colour is variegated and very brilliant when (he fish is 

 first caught. Tlie entire surface of its body has a tin or dim silvery lustre. 

 The back is of a dark olive-green colour : the spines are translucent, and 

 partake of the amber tint of the iris ; and the fins and tail are intermediate 

 between an amber and a mottled vandyke-brown hue. 



Latebal link. The lateral line is smooth, solitary, superior, straight, 

 and descending. 



