MALACOPTERYGII ABDOMINALES, 
317 
less disagreeable than that of the other Siluri. Some American species, with the head small, rounded, and blunt, 
having tln-ee cirri, and the eyes scarcely perceptible, may form a new subgenus. 
Mystus, are Siluri with a second or adipose dorsal fin. They are found in the waters of Guiana. 
body naked, and no lateral armature; but the subgenus requires division and subdivision. First, 
Bagrus has small crowded teeth in both jaws and the vomer, and may be subdivided by the number of cirri, and 
the shape of the head. With eight cirri, some have the head long and depressed, and others short and broad. 
With six cirri, some have the snout as depressed, and broader than that of the Pike ; others have the head oval, 
and a kind of helmet of shagreen-like bones ; in others, the head is round and naked ; while others, again, have 
the head greatly depressed, the eyes low down, and the adipose fin very small ; and there are yet others which 
have only four cirri. [Some of these, as Pimelodes cyclopum, are ejected in hot water from volcanoes.] 
Pimelodes, properly so called, want the teeth in the vomer, but often have them in the palate ; the cirri and 
form of the head differ more than in the preceding subgenus; some have but a single row of teeth ; some have the 
head helmeted, and a distinct bony plate between the helmet and the dorsal spine ; others have a single plate from 
the snout to the dorsal ; others, again, have the head oval and naked ; some with six cirri, and others eight ; some 
with a large naked head are called Cats, which have six or eight cirri ; then there are others which have the head 
small and flat, the dorsal minute, and the teeth scarcely perceptible ; there are others still which have teeth on the 
palatals, sometimes like velvet, or like a card, with a buckler on the nape, distinct or united to the helmet, and 
tha'palatal teeth sometimes like a helmet ; some singular ones have teeth like a card, under the skin of the cheek, 
and moveable ; others yet have a lengthened snout, or a pointed one, nearly toothless. These last lead to,— 
Synodoniis, with the snout narrow, and the lower jaw supporting an assemblage of teeth laterally flattened, 
ending in hooks, and individually attached to flexible peduncles. The helmet extends in one plate to the first 
spine of the dorsal, which is very strong, as are also those of the pectorals ; the cirri, afld sometimes the maxil- 
laries, are barbed. They are found in the Nile and other African rivers, but are not eaten. 
Ageniosus. Some of these have the maxillary turned up in a kind of toothed horn, instead of a fleshy cirrus ; 
and others have it concealed under the skin, with the dorsal and pectoral spines scarcely visible. 
Doras, have an adipose dorsal, with plates in the lateral line, armed with keels or spines ; the dorsal and pectoral 
spines strongly toothed, the helmet rough, and the shoulder-bone pointed backwards. Some have teeth only in 
the upper jaw; others have the snout pointed, and the teeth absent, or hardly visible, with occasional lateral 
bristles to the cirri. 
Heterobranchus, head broad, from the helmet having two lateral pieces of the frontal and parietal bones ; oper- 
culum smaller, but with a tree-like ramification on the third and fourth gill-arch, as a sort of supplemental gills.; 
viscera like the rest of the.family, but they have from eight to fourteen gill-rays, strong pectoral spines, no dorsal 
one, and the body long and naked. They inhabit the rivers of Africa, and some of those of Asia. Their flesh is 
indifferent, or bad. 
One of them, however, Macropteronotes, with a single indented dorsal, constitutes a considerable article of food 
in Egypt and Syria, where it is called the Sharmuth, or Black Fish. Others have a dorsal with rays, and also an 
adipose one. Protosus, have a second dorsal, with rays ; and this and the anal long, and uniting to form a tail 
like an Eel ; lips fleshy ; conical teeth in front of the mouth, globular ones behind, and those above placed on the 
vomer; skin naked; nine or ten gill-rays ; eight cirri; and a singular branched appendage behind the vent, be- 
sides the tubercle common to the family. Some have large and toothed dorsal and ventral spines ; others have 
them almost concealed under the skin. They are found in the East Indies. 
Callichthys, have the sides armed with four rows of scaly plates ; head the same, but the snout and under-part 
of the body naked ; one ray in the second dorsal ; pectoral spines strong, and dorsal one feeble ; mouth small ; 
teeth barely visible ; four cirri ; eyes small, and lateral. They can crawl out of the water like an Eel. [These are 
the subgenera of Silurus] . 
Malaptherurus, has no dorsals with rays, but only a small adipose one in the tail, and no spines in the pectorals. 
The skin is smooth ; the teeth small and crowded, and are ranged into a broad crescent in each jaw ; there are 
seven gill-rays ; and the jaws and viscera are like those of Silurus. M. electricus,X\ie Raasch, or Thunder-fish of 
the Arabs, is the only known species. It has six cirri, and the head more slender than the body, but enlarged in 
front. Like the Torpedo and Gymnotus, it can communicate an electric shock, the organ of which is situated 
between the skin and muscles, and consists of a cellular tissue, inclosing a fluid, and abundantly furnished with 
nerves. It is found in the Nile, and the rivers of Central Africa. 
Aspredo, have the head flattened, and the anterior part of the body much widened ; the tail long; the eyes small, 
and placed upwards ; the intermaxillaries under the ethmoid directed backwards, and with teeth on the posterior 
edge only ; and they have the whole gill apparatus immoveable, being soldered to the temporal bone and the pre- 
operculum ; gill-opening a mere slit behind the head, the membrane of five rays adhering everywhere else ; the 
lower jaw is transverse, and shorter than the snout ; the first ray of the pectorals is more toothed than in any 
other of the family ; there is but one dorsal, with a weak first ray ; but the anal is long, extending under the long 
and slender tail. Some have six cirri, some eight ; and, in the latter case, one pair are attached to the maxillaries, 
the others to the lower jaw in pairs. 
Loricaria, have hard angular plates on the head and body ; small intermaxillaries suspended under 
the muzzle ; transverse disunited mandibles, supporting hooked teeth, which are long, slender, and 
flexible. A large membranous veil encircles the opening ; the pharynx is furnished wdth numerous 
pavement teeth ; the gill-lids are immoveable, but two small plates supply their places ; they have four 
