202 



Malacop. 



tervfrii 

 Abilomi- 



nales. 

 SiluriilDP. 



ICHTHYOLOGY. 



FAMILY III— SILURID/E. 



Is distingiiislied from all the others in the order by hav- 

 ing no true scales, but only a naked skin, or large osseous 

 plates. The inter-maxillaries, suspended under the eth- 

 moid, form the edge of the upper jaw ; and the maxillaries 

 are reduced either to mere vestiges, or are lengthened 

 into barbels. The intestinal canal is large, folded, and 

 without caeca ; the bladder large, and adhering to a pe- 

 culiar osseous process ; the dorsal and pectorals have al- 

 most always a strong articulated spine for the first ray, 

 and there is very frequently an adipose fin behind, as in 

 the SalmonidsB. 



Genus Silurus. A numerous genus, known by its 

 want of scales, the mouth cleft at the end of the snout, 

 and, in the greater number of sub-genera, by the first ray 

 of the pectoral being composed of a strong spine. Tliis 

 is articulated to the shoulder bone, in such a manner that 

 the animal at pleasure can either draw it towards its body 

 or erect it perpendicularly, in which case it becomes a 

 dangerous weapon, and inflicts wounds which in some 

 countries are considered venomous, doubtless because 

 tetanus or lock-jaw sometimes ensues. The head of the 

 Siluri is depressed ; the maxillaries very small ; and the 

 covering of the branchiae wants that piece which has been 

 named by Cuvier the sub-opercle. 



In some species (Sibinis, Lacep. properly so called) 

 there is only one small fin, with few rays on the anterior 

 part of the back, but the anal is very long, and reaches 

 nearly to the caudal. In others, more especially so nam- 

 ed by Artedi and Gronovius, the small dorsal is without 

 any apparent spine ; the teeth on both jaws are like those 

 of a wool card, and behind the inter-maxillary band of 

 teeth there is a vomerian band. Of this kind of structure 

 an example is found in Silurus glanis, L. which is the 

 largest of European fresh-water fishes, and the only one 

 of this extensive genus inhabiting the Continent. See 

 Plate CCCIV. fig. 12. It is smooth, greenish black, spot- 

 ted with black above, and yellowish-white beneath. The 

 head is large, with six barbels. It sometimes attains the 

 length of twelve or fifteen feet, and the weight of 300 or 

 400 pounds. As this creature is somewhat unwieldy in 

 its motions, it does not pursue its prey, which consists of 

 small fishes, but lies concealed among the mud, and seizes 

 such unwary stragglers as happen to come within reach. 

 It has occasionally been observed in the sea, but always 

 near the mouths of rivers, and in such other situations as 

 to leave no doubt that its appearance there is to be as- 

 cribed to accidental causes. The flesh is fat and sweet, 

 and its lard has been employed in some places as a sub- 

 stitute for that of the hog. Sir Robert Sibbald, at the 

 conclusion of his list of river fishes, adds, " Silurus sive 

 Glanis ;"' from which it has been inferred that this gigan- 

 tic species may at one period have inhabited the Scottish 

 rivers.^ 



A few fishes, found hitherto only in the Nile, differ from 

 the Siluri in having their bodies compressed vertically, and 

 by having a strong and denticulated spine to the dorsal. 

 Their head is small and depressed, the nape suddenly raised, 

 and the eyes placed very low — circumstances which be- 

 stow upon them a very singular appearance. They consti- 

 tute the genus Schilbus. The Pimelodi of Lacepede 

 are characterised by the body being covered only by a 

 naked skin, without lateral armature. This definition, how- 

 ever, comprehends a great number of fishes, many of which 

 present so many differences in appearance and structure, 

 that it is necessary that they should be grouped in several 



subordinate genera. The first of these, established by 

 Cuvier, and which he names Bagrus, has in each jaw a 

 band of small crowded teeth, and behind those of the up- 

 per jaw a parallel band which belongs to the vomer. They 

 admit of still further subdivision, from the number of their 

 barbels and the form of their head. Among those having 

 eight barbels, some have the head oblong and depressed ; in 

 others it is broad and short. Of such as are furnished with 

 six bar'^^els, the most remarkable have the muzzle depres- 

 sed anci broad, after the manner of the pike ; while others 

 have the head of an oval form, and its shagreened bones 

 forming a kind of helmet. The Pimelodi, however, /)ro- 

 perly so called, have no band of teeth on the vomer, paral- 

 lel to that of the upper jaw, but there are often some on 

 the palatines. In the number of their barbels, and in the 

 form of their heads, these fishes present still more nume- 

 rous varieties than the Bagri. Thus, among such as have 

 only a single band of teeth, some are observed to have the 

 head helmeted, and a distinct osseous plate or buckler be- 

 tween the helmet and the spine of the dorsal. Such is Sil. 

 clarias, Bl. xxxv. 1, 2. In others the buckler is united to 

 the helmet, and forms only a single body with it, the hel- 

 met thus extending from the muzzle as far as the dorsal. 

 In some instances the head is oval, clothed only by the 

 skin, through which the bones do not appear ; in this 

 group the species have either six or eight barbels. In 

 those called cat-Jish, the head is naked but very broad, 

 and their barbels also vary, according to the species, from 

 six to eight. We ought probably to place here the Mathe- 

 megh of the Cree Indians (Silurus felis, Gm. ?), described 

 by Dr Richardson as found sparingly in the lakes that flow 

 into the Saskatchewan, and more abundantly in the lakes 

 and rivers to the southward. It is much prized as a rich 

 food.^ Numerous other modifications of structure are to 

 be found in this extensive genus, of which the greater pro- 

 portion of the constituent species have but recently become 

 known to naturalists. Several have the muzzle elongated, 

 and these lead to a group of still more remarkable confor- 

 mation, viz. 



Genus Synodontis, Cuv. In which the muzzle is nar- 

 row, and the lower jaw supports a packet of teeth much 

 flattened laterally, terminating in hooks, and each suspend- 

 ed by a flexible pedicle ; a kind of dentition of which no 

 other example is known. The rough helmet, formed by 

 the cranium of these fishes, is continuous, without any in- 

 terruption, with an osseous plate, which extends to the 

 base of the spine of the first dorsal ; and that spine is very 

 strong, as is likewise the case with those of the pectorals. 

 The lower barbels, and sometimes also the maxillaries, 

 have lateral barbels. The species are found in the Nile 

 and Senegal, and are known to the inhabitants of Lower 

 Egypt by the general name of Schal, while in the upper 

 regions of the same country they are termed Gurgur. 

 Their flesh is not accounted of any value. The Age- 

 NEiosrof Lacep. possess all the characters of the Pimelodi, 

 but they are without the barbels properly so called. Silu-' 

 Tus inermis (Bl. 363) affords an example. 



Genus Doras, Lacep. Contains such Siluri as have 

 a second adipose dorsal, and the lateral line defended by 

 a row of osseous pieces, each relieved by a spine or pro- 

 jecting keel. Their dorsal and pectoral spines are very 

 strong, and powerfully dentated. Their helmet is rough, 

 and is continued as far as the dorsal, as in Synodontis. and 

 the humeral bone forms a point behind. 



Genus Heterobranciius, Geoff. Has the head pro- 

 vided with a rough, flat buckler, wider than in any other 

 of the Siluri, because the frontals and parietals produce 



Malacop. 



terygii 



Abilniiii- 



nale.°. 

 Siluridae. 



' Scoiia lUustrata, p. 25 



» Appendix to Captain Franklin's first Voyage to the Polar Seti, p. 12i 



' Fleming's British Animals, p. 



198. 



