FISHES HETEROLEPIDAE OPLOPOMA PANTHERINA. 47 



upon tlie superior posterior part of the orbit, being about three-eigbths of an inch long and balf 

 as broad where broadest, inserted transversely, so as to lean backwards and slightly downwards 

 along the orbit. The lower jaw is longer than the upper. The mouth is slightly oblique 

 upwards and rather large, since the posterior extremity of the maxillary extends to a vertical 

 line drawn somewhat posterior to the entire orbit. The jaws are furnished with canine teeth 

 of different size ; the largest may be observed upon the branches of the dentaries and upon the 

 vomer ; the next in size are on the premaxillaries and the palatines. All these are accompanied 

 by small conical and acerated teeth, irregularly distributed over the bones upon which they are 

 inserted ; a group of them may be seen on each side of the symphysis of the premaxillaries. 

 The surface of the tongue is perfectly smooth, thin, and pointed anteriorly. The eye is well 

 developed ; sub-elliptical in shape ; its longitudinal diameter entering about six times in the 

 length of the side of the head. There are two nostril openings on either side, quite apart from one 

 another ; the anterior, which is the largest, is situated in advance of the eye, being much nearer 

 the orbit than the extremity of the upper jaw ; the posterior is placed upon the anterior superior 

 rim of the orbit. The convexity of the preopercle is provided with some short and obtuse 

 spines, or rather obtuse processes, mostly hidden under the skin. The rest of the opercular 

 bones are smooth and without spines ; the opercle has the shape of an acute triangle, with its 

 summit pointing obliquely towards the back, having at its inferior edge a prominent subopercle, 

 extending beyond the summit of the opercle, and likewise in a very oblique position. The 

 interopercle is also a well developed bone. The gill openings are very widely open, in the 

 shape of an obtuse curve, extending beneath to the hyoide apparatus, and continuous from both 

 sides. The branchiostegals are well developed, six in number, on either side. 



The anterior dorsal is nearly twice the length of the posterior, and a little higher upon its 

 middle. It commences at a short distance from the occiput, in advance of a vertical line which 

 would intersect the limb of the preopercle. It is composed of twenty-four spinous and acerated 

 rays, the four anterior being shorter than the sixth and the following, simulating together an 

 independent fin, though much less distinctly than in Heterostichus rostratus. The second dorsal, 

 which is united to the first at its base, is composed of twenty-one articulated rays, with two 

 rudimentary ones and a small spine upon its anterior margin, from which a membrane is sent 

 to the posterior spine of the first dorsal. Most of the articulated rays of the second dorsal are 

 bifurcated twice. The caudal fin, which constitutes a little less than the eighth of the total 

 length, is posteriorly concave or sub-crescentic, and composed of twelve branched and two undi- 

 vided rays, with a few rudiments on each side. The origin of the anal is nearly opposite the 

 anterior margin of the second dorsal, with which it is even posteriorly. It is a lower fin, com- 

 posed of twenty-one articulated rays and a small spine concealed in the skin at its anterior 

 margin. Most of the rays are bifurcated, and the interradial membrane emarginated through- 

 out. The ventrals are well developed, composed of five branched rays and a rather strong 

 spine, though covered by the integuments. Their insertion takes place posteriorly to a vertical 

 line passing immediately behind the base of the pectorals. Their posterior extremity does not 

 extend as far as the tips of the latter fins, and leaves the vent far off. The insertion of the 

 pectorals is quite oblique and reaches the inferior surface of the thorax ; they are very large, 

 broad, and long, composed of seventeen articulated and branched rays, the inferior ones stouter 

 and shorter, with their interradial membrane emarginated, 



Br. VI— VI; D XXIV, 23; A I, 21 ; C 2, 1, 6, 6, 1, 2; VI, 5; P 17. 

 The vent is placed considerably in advance of the anterior margin of the anal, and provided 

 posteriorly with a fleshy, sub-conical appendage. 



