ICHTHYOLOGY. 



203 



Malai'op- 

 teryi;ii 



AbdiiRii- 

 nales. 



Siluridoe. 



lateral plates which cover the orbit and the temple. The 

 operclc is still smaller in ])roportion than in the foregoing 

 genera, and the peculiarity observed by Geoffroy distin- 

 guishes them from all other fishes, viz. that besides the or- 

 dinary hranchiiv, they have ramified appendages like trees 

 adhering to the superior branch of the third and fourth 

 branchial arch, and which appear to be a kind of supernu- 

 merary branchia;. All the species pertaining to this genus 

 are found in the Nile, Senegal, and a few of the Asiatic 

 rivers. Their flesh is either of indifferent quality, or alto- 

 gether imfit for food. This is not the case, however, with 

 the Sharmuth or Blncfi-Jish ( Sihiriis ajiguillaris, Hasselq.), 

 which is common in Egypt and Syria, and constitutes in 

 the latter country a valuable article for the table. 



Genus Plotosus, Lacep. Is characterised by a second 

 radiated dorsal, of great length, as well as the anal ; and 

 both uniting at the caudal, form a point, as in the eel. 

 Their lips are fleshy and pendent ; the throat armed an- 

 teriorly with conical teeth, behind which there are others 

 of a globular form, which at the upper jaw jiertain to the 

 vomer. The head, as well as the rest of the body, is en- 

 veloped in a thick skin, and the branchial membrane has 

 nine or ten rays. All the known species are from the 

 East Indies. They have eight barbels, and, behind the 

 anus, the fleshy and conical tubercle common to all the 

 Sihiri ; and there is, besides, a fleshy ramified appendage, 

 the functions of which, though unknown, are [)robably re- 

 markable. Some have the dorsal and pectoral spines 

 dentated, and of considerable size. Such is Platystacus 

 anrjuillaris, 151. 373, while others have them concealed 

 beneath the skin. The latter is the case with Plotosus 

 cashis, Buchan. xv. 44. Certain fishes referred by Lin- 

 naeus to the genus Callichthys, and pertaining to that nam- 

 ed Cataphractus by Lacep., have their bodies almost 

 entirely cuirassed, so to speak, on its sides, by four rows 

 of scaly pieces ; and there is likewise on the head a com- 

 partment of these pieces. The extremity of the muzzle, 

 however, is naked, as well as the under side of the body. 

 The second dorsal has but a single ray in its anterior 

 edge; the pectoral spine is strong, but the dorsal is slen- 

 der or short. The mouth is but little cleft, and the teeth 

 nearly imperceptible ; the barbels, four in number ; the 

 eyes small, and placed on the sides of the head. These 

 fishes can crawl for some time on dry land like the eel. 

 In some the pectoral spine is merely rough, in others it is 

 dentate, as in the majority of the Sihiri. 



Genus Malapterurl's, Lacep. Distinguished from 

 all the true Sihiri by having no rayed fin upon the back, 

 but only a small adipose one on the tail, and by the want 

 of a spine to the pectorals, of which the rays are entirely 

 soft. But one species is known with six barbels, the head 

 not so thick as the body, which is inflated in front. It is 

 the famous electric Silurus (Siltirus ehctricus, Linn.) of 

 the Nile and of Senegal ; the Raash or Thunder of the 

 Arabs, which gives electrical shocks like the Torpedo and 

 Gymnohis. It appears that the seat of this faculty is a 

 particular tissue situate between the skin and muscles, 

 and which presents the appearance of an adipose cellular 

 substance, abundantly supplied with nei'ves. 



Genus AsPREDO, Linn. Platystacus, B\. Presents very 

 peculiar characters in the flattening of the head, and the 

 enlargement of the anterior part of the trunk, which prin- 

 cipally results from the size of the humeral bones ; in the 

 proportional length of the tail ; in the small eyes placed 

 in the superior face ; and in the inter-maxillaries being in- 

 clined under the ethmoid, directed backwards, and bear- 

 ing teeth only on the hinder edge. In addition to these 



peculiarities, they are the only osseous fishes known which 

 have no mobility in the operculum, because the pieces 

 which ought to compose it are soldered to the tympanum 

 and pre-opercle. Only a few species have come under 

 the cognizance of naturalists, such as the Silurus Asjiredo, 

 Linn. ; Plat, cotylep/iortis, Bl. 372 ; Silurus hexadacti/lus, ' 

 Lacep. They have six or eight barbels, and it is remark- 

 able, that when there are eight, one pair is attached to the 

 base of the maxillary barbels ; the four of the lower jaw 

 are in pairs, one behind the other. Globules are seen on 

 some of these fishes, which appear to be their eggs, ad- 

 hering to the thorax by means of pedicles. 



Genus Loricaria, Linn. Is so named on account of 

 the rigid angular plates which completely cover the body 

 and head, as with a coat of mail, and is further distin- 

 guished from such kinds as possess a somewhat similar 

 defensive armour by having the mouth pierced under 

 the muzzle. In position and mode of conformation, this 

 mouth is most analogous to that of Synodontis ; the inter- 

 maxillaries are small and suspended under the muzzle, 

 and the mandibular bones, which are transverse and sepa- 

 rate, bear long flexible teeth, terminating in a hook. A 

 broad, circular, and membranous veil surrounds the aper- 

 ture ; and the pharyngeal bones are garnished with nu- 

 merous teeth e«/)at'e. The trueopercula are immoveable, 

 asin^«/)reffo,but twosmall, moveable, external plates seem 

 to perform their office. The branchial membrane has four 

 rays ; and the first rays of the dorsal and pectorals, and 

 even of the ventrals, are strong spines. There is neither 

 ca?ca nor air-bladder. The species may now be arranged 

 in two sub-genera, viz. Hypostoma, Lacep., which has a 

 second small dorsal, provided with a single ray, as in 

 Callichthys. Their labial veil is simply papillose, and 

 bears a small barbel on each side. They have no plates 

 under the belly, and the intestines, which are spirally 

 convoluted, are as slender as a pack-thread, and twelve or 

 fifteen times longer than the body. They are caught in 

 the rivers of South America. Loricaria plecostomus, Linn., 

 Bl. 376, and Hyp. etentaculatum, Spix, iv. are examples 

 of this sub-genus. Loricaria, properly so called, has 

 but a single dorsal in front : their labial veil is garnished 

 on its edges with many barbels, and sometimes covered 

 with villosities ; the belly is defended by plates, and the 

 intestines are of moderate thickness. To this group be- 

 long L. cataphracta, Linn. ; L. rostrata, Spix ; Rinelepis 

 aspera and Acanthicus hystrix, Id. 



FAMILY IV.— SALMONID^.' 



The fourth family of the Malacopterygii of Cuvier is 

 composed almost entirely of the Linniean genus Salmo, 

 and has in consequence received from modern Ichthyolo- 

 gists the title of Salmonid^. It will remain, however, to 

 future observation to determine whether the family shall 

 take its title from the salmon, as typical of the form, or 

 from some other group, leaving to the above-mentioned 

 fishes the value of a sub-family only. As it is, the circum- 

 stance of the present Salmonidae possessing a small adi- 

 pose fin, placed between the dorsal fin and the tail, has 

 been used in a light purely artificial, and too much conse- 

 quence has been attached to it. Mons. Agassiz is of opi- 

 nion that the Clupeas should be added to them, as diflering 

 only in the want of this fin ; while all the Salmones of Cu- 

 vier do not possess a true adipose fin, — that part being 

 composed of rays in the genera Serrasalmus and Myletes. 



The family, as it now stands, may be characterised by 



Jlalacop- 



terygii 

 Abdocni- 

 nales. 

 Salmo. 

 iiidse. 



' As an illustration of the SaljioniDvE, we here figure (from IMr Griffith's Animal Kingdom) Salmo Canademit, a North American 

 species, beautifully spotted with blood rid on a white circle. See Plate CCCV. fig. I. 



