1 6 Fishery Board for Scotland. 



the vomer and the palatine ridges. Horizontal membranes join inside 

 the moiith, the jd rem axillae, and the dentaries respectively. The 

 number of fin-rays in the several fins is given below. The hind edge 

 of the tail lin is slightly concave. The dorsal and ventral edges of 

 the base of this fin form somewhat sharp ridges. 



The lateral line is slightly bent. 



The head is adorned externally by a number of teeth. In two 

 fishes, 48 and 49 cm. long, the teeth on the top of the head were 

 arranged as follows : — One tooth projected over the orbit. A ridge 

 over the top of the orbit ended posteriorly in a little tooth. Two 

 isolated teeth were found further back on nearly the same line. On 

 the head still further behind a prominent plain ridge runs backwards 

 and outwards on each side : it may end in a little tooth. Between 

 the ridges the top of the head is flat or very slightly hollowed. The 

 interorbital space is flat or slightly depressed. The teeth on the side 

 of the opercular bones, and at the beginning of the lateral line, are 

 indicated in the figure. 



A marked feature in the appearance of the fish is the hump 

 immediatelj" in front of the beginning of the dorsal fin. The lower 

 jaw is prominent. 



The eye is large : the cornea is loose. The cornea is a translucent 

 portion of the skin of the head. The orbit is round. 



The scales are ctenoid (Fig. 61). No attempt was made to intro- 

 duce the exact number or size of scales into the drawing (Fig. 56), but 

 their general distribution is indicated. The outside of the lower 

 jaw is covered with scales. They are well seen in large specimens, 

 e.g., 48 and 49 cm. in length. In small examples, e.g., 20 cm. long, 

 the}'' were detected on the posterior half of the jaw only. 



The peritoneum is black. The swim-bladder is large. The ureter 

 is median. 



The pyloric cseca were 8 or 9 in number in both large and small 

 fishes (three specimens of each). 



The first hgemal spine is forked at its extremity (Fig. 97). The 

 angle varies in depth. The point of the first interspinous bone of the 

 anal fin enters and is bound to the fork of the first hgemal spine. 

 The interspinous bone forms the hind Ijorder of the adominal cavity. 



A comparison was instituted between 54 fishes measuring from 

 17*4 to 24 cm., and 4 Iceland fishes measuring 39 and 42 cm, in 

 length. The small fishes were, with two exceptions, pregnant 

 females. They showed the dark bars more prominently. The 

 characters selected for comparison were (a) the horizontal diameter 

 of the orbit, {!>) the distance from the tip of the mandible — when the 

 mouth was closed — of the following points, viz., the beginning of the 

 pectoral, ventral, dorsal and tail fins, the anterior edge of the orbit 

 and opercular cleft. The numbers of fin-rays and vertebras were also a 

 basis for comparison. The fish was laid on a centimeter scale, and 

 the distances were marked oflT on the scale by means of a needle. 

 The distances are taken along the longitudinal axis of the fish. 

 Agreement was found in respect to the measurement characters 

 between the two lots of fishes except in three characters, viz.: — The 

 orbit in the smaller fishes was the larger. It measured in horizontal 

 diameter 9"2 to 11 '3 per cent, of the length of the fish. The length 

 of the fish in this case is the distance from the tip of the mandible, 

 when the mouth is closed, to the end of the middle rays of the tail fin. 



