690 



S I L U R U S. 



taken in the Oder. When they are once discovered 

 they are not very difficult to capture, as their motions 

 are slow ; but they are very tenacious of life. It 

 does not appear that they can be introduced with 

 success into any rivers except those in which the 

 water is very cold, which is an additional reason for 

 concluding that they are not the same species which 

 is met with in the warm countries. 



Schilbeus. This is one of the subdivisions of the 

 genus Silurus, and it occurs chiefly in the Nile, 

 where there are two species, both much sought after 

 on account of the flavour and wholesomeness of their 

 flesh. Their characters, as distinguished from the 

 European species, are : the body compressed ver- 

 tically ; the head small and depressed ; the neck 

 rising suddenly to a considerable elevation ; the eyes 

 very low, giving a singular expression to the head ; 

 the lips furnished with eight barbules, four on the 

 extremity of each jaw; and the spine of the first ray 

 of the dorsal very strong and toothed. There are at 

 least two species in the Nile, the one called Schilbe 

 by the Arabs, and the other Schilbe oudney, which 

 last word means eared ; and the systematic name is 

 only the Arab one with a Latin termination. The 

 chief distinction of the two species is that the first 

 has seven rays in the dorsal, eleven in each of 

 the pectorals, six in the ventrals, sixty-five in the 

 anal, and eighteen in the caudal ; while the second 

 has eleven in the pectoral, six in the ventral, 

 seventy-seven in the anal, and eighteen in the caudal. 

 They appear to live more indiscriminately in fresh and 

 salt water than the Silurus of Europe ; for, according to 

 the accounts, they are found in the Red Sea as well as 

 in the Nile, and the Red Sea receives a smaller supply 

 of fresh water than any other sea of the same extent ; 

 but, at the same time, it is one of the most productive 

 of animal life any where to be met with on the sur- 

 face of the globe. There appears to be an American 

 species of this genus, which has the head small and 

 blunt, and the eyes so very minute that they are 

 hardly visible. 



Mystus. The fishes of this subgenus are mostly 

 found about the mouths of rivers in the tropical seas, 

 especially in the Atlantic. They are covered with a 

 smooth waked skin without any armature on the sides ; 

 and they have an adipose dorsal fin behind the one 

 with rays. They are very common about the mouths 

 of the rivers in the West Indies, and on the north 

 coast of South America. 



Pimelodus. These have the skin soft and smooth, 

 and they are without teeth on the vomer, but they 

 have some on the palatal bones. They vary con- 

 siderably from each other in the shape of the head 

 and the form of the barbules on the lips. There are 

 some of them which have only a single row of teeth, 

 and these have usually a bony plate on the upper 

 part of the head, and another on the neck between that 

 one and the spine of the dorsal fin. Others have these 

 two osseous pieces meeting each other, and forming 

 one large shield, which extends nearly the whole way 

 from the muzzle to the first dorsal fin ; and there are 

 others which have the head covered with the common 

 integument the same as the rest of the body. In fact, 

 the varieties in the form of the head, and in the arma- 

 ture, whether of teeth internally or of plates on the 

 outside, are numerous. The diversities in these re- 

 spects are so great, that the fishes are quite a study, 

 although, in their appearance to outward observation, 

 they all have a very strong common likeness. 



Porcus. These have the teeth in the upper jaw 

 composed of two parallel bands of thickly-set small 

 teeth, one upon the intermaxillary bones, and the 

 other on the vomer ; the head is smooth, and the 

 plate on the nape very small ; some of them have the 

 snout extended similar to that of the pike. There 

 are several species of them found chiefly on the shores . 

 of Africa and its islands, and also in the larger rivers 

 of that quarter of the world. 



Synodontis. The. teeth of this division are very 

 peculiar and quite unique among toothed animal?, 

 much as these differ from each other. They have in 

 the lower jaw a patch of teeth very much flattened 

 laterally, but ending in crooked points, and standing 

 upon flexible peduncles ; they have a rough helmet 

 on the head which extends in a bony plate as far as 

 the base of the dorsal spine ; that spine is also very 

 strong and toothed. They are found in the larger rivers 

 of Africa, but their flesh is of comparatively little 

 value. 



Argeneisos resemble the Pimelodus, only they are 

 without the barbules at the mouth, though some of 

 them have the maxillary bones continued in a sort of 

 horny projections. 



Doras have a row of osseous plates along the lateral 

 line, each of which has an elevated keel terminating 

 in a spine. Some of them are found on the coasts 

 of North America, but not in high latitudes. 



Heterobranchus. The fishes of this sub-genus are 

 named from the very peculiar form of their gills. 

 They have the gill-openings, and especially the gill- 

 covers, smaller than in most of the family ; and on 

 the superior branch of the third and fourth bronchial 

 arches there are tree-like appendages, which have 

 some resemblance to the gills of tadpoles, and to 

 those of the young sharks, while they continue en- 

 closed in the egg. They have a rough and flat plate 

 on the head, broader than in any other of the family, 

 and having lateral plates which extend over the tem- 

 ples and the orbits of the eyes. They have a strong 

 toothed spine in the pectoral, but none in the dorsal. 

 There are a good many species of them, some with a 

 second dorsal, and some without. They inhabit the 

 rivers of Africa and Asia, and are especially abundant 

 in those parts of the two quarters which lie most ad- 

 jacent to each other. Generally speaking, their flesh 

 is of inferior quality ; but there is one, the Sharniut/i, 

 or black fish, which is so abundant in Syria as to form 

 a staple article in the food of the people. 



Plotosus. The members of this sub-genus are dis- 

 tinguished from all the others by having two dorsal 

 fins with rays to both. The second dorsal and the 

 anal are both very long, and they meet at the extre- 

 mity of the fish, forming a tail something like that of 

 an eel. The lips are fleshy and prominent, their 

 gape is armed in front with conical teeth, and behind 

 these there are globular ones which, in the upper jaw, 

 are situated upon the vomer. They have no naked 

 plate on the head, but a covering of thick skin the 

 same as on the body. The spines of the fins vary a 

 good deal, some having them large and toothed, and 

 others wholly concealed within the skin. They are 

 mostly fishes of the oriental seas; and some, even 

 of very small size, are very dangerous to handle, in 

 consequence of the formidable character of these 

 spines. One is mentioned, not above two inches in 

 length, the wounds given by which are of so lacerated 

 and ragged a character that, after handling it much, 

 the hands cannot be moved for five or six days, and 



