146 



PLEURONECTID^. 



THE FAMILY OF FLAT FISHES. 



A TOTAL want of uniformity between the sides of the head, 

 and also generally of the body. Both of the eyes are on one 

 side of the head, while the nostrils generally maintain their 

 position in pairs on each side of the summit. The mouth is 

 twisted, so that the two corners do not answer to each other, 

 and within the mouth there is generally a veil or cross mem- 

 brane above and below. The body is much compressed; one 

 side bearing colour, the other without it, and the structure of 

 the skin differs in each. The abdominal cavity very short, 

 but the lobes of roe are contained for the most part in a 

 recess which passes backward between the muscles towards 

 the tail. The vent close to or enclosed between the ventral 

 fins, which are near the throat. The fins nearly encircle the 

 body, and the dorsal fin begins on the top of the head or in 

 front of it. 



In most . if not all of these fishes the spinous processes of 

 the vertebrae which support the rays of the dorsal fin, and are 

 anterior to the pelvis, are turned forward for that purpose; 

 while those of the vertebrae on the same line of the back that 

 are near the tail are directed backward. On the abdominal 

 side all the spinous processes behind the abdomen itself are 

 directed more or less backward. It is an essential part of the 

 structure of these fishes that the superior and inferior processes 

 of the vertebra? are very long, and those of the sides very 

 short; but in the Carter, and perhaps in others of this family 

 which possess a lengthened form, while the superior and 

 inferior processes are comparatively shorter, the lateral processes 

 are somewhat more developed. In the Topknot the spinous 

 processes of the vertebras are remarkably long, and anterior 

 to the first of these processes there are numerous (what we 



