496 PISCES SUB-CLASS III.TELEOSTOMI. 



Section B. Nematagnathi. 



The second section of the Physostomi includes only the cat-fishes or sheath- 

 fishes, typified by the huge wels (Siluriis glaitis) of the larger rivers of 

 Eastern Europe, which is the sole European representative 

 Cat-fishes. of this immense family. Apart from the structural features 

 Family distinctive of the section, the cat-fishes are characterised by 

 SiluridcB. the skin of the body being either naked, or protected by 

 bony plates of variable size, scales being invariably wanting. 

 In all, the mouth is provided with barbels, or feelers, frequently of great 

 length, and it is from the presence of these highly sensitive organs that the 

 name of cat-fish is due. Many of them have the bones of the hinder region 

 of the skull ornamented with a rough tubercular sculpture, and there is fre- 

 quently a large shield, similarly sculptured, covering the upper surface of the 

 neck and shoulders. Often, too, the front of the dorsal fin is armed with a 

 long, powerful, and sometimes poisonous, spine, which in some forms can be 

 raised or depressed by the aid of a kind of trigger-like arrangement connected 

 with the spines of the vertebrae of the neck. Very often there is a fatty 

 dorsal fin, and there is also a rayed dorsal. In the skull the margin of the 

 upper jaw is mainly formed by the premaxillse ; but a more important char- 

 acter is to be found in the absence from the gill-cover of the bone technically 

 known as the subopercular. The air-bladder, which may be bony, is very 

 generally present, and is then connected with the internal ear by means of 

 minute bones. Cat-fishes are ugly creatures, with large ungainly heads, 

 small eyes, and the aforesaid long barbels. Some, like the Oriental Bayarius 

 yarelli, grow to a length of a couple of yards, and have huge ugly mouths, 

 opening nearly the full width of the head. In habits they are sluggish, and 

 dwell for the most part on the bottom of muddy rivers, lakes, or ponds, 

 where their barbels probably play a large part in enabling them to find their 

 way about. They are remarkably tenacious of life, and the writer once found 

 it absolutely impossible to kill some of these fish, caught while he was 

 quarantined on board ship in the Rio de la Plata. All these fishes should be 

 handled with extreme caution, as the spines of many of them are capable of 

 inflicting extremely dangerous wounds. Their flesh, although eatable, is of 

 poor quality. In the rivers and lakes of India and other Oriental countries, 

 cat-fish are extremely abundant, as they also are in those of South America, 

 where the shores of every little pond is strewn with their skulls. They 

 appear to inhabit ponds or lakes liable to be dried up in seasons of unusual 

 drought, and at such times they doubtless are enabled to survive by burying 

 themselves deep down in the mud. Although the majority are fresh-water 

 fishes, some will enter salt water temporarily, while others are permanent 

 residents there. For the most part they keep near the coasts, but from the 

 circumstance that one species is common to the rivers of India and some of 

 the Malayan countries, it would seem that certain kinds occasionally traverse 

 a considerable extent of sea. In certain forms, like the members of the 

 genus Arius, the males are in the habit of taking charge of the nursery 

 arrangements, by carrying the eggs about with them in their mouths. Since 

 the family comprises considerably more than a hundred distinct genera, it is 

 obviously impossible to give any adequate account in a work of the present 

 nature. It is sub-divided into several sections, in the first of which the 

 dorsal and anal fins occupy the greater part of the length of the body, the 



