

siluroidete. 133 



suspended to the ethmoid, and not protractile, the labials very small, but almost 

 always prolonged into a fleshy barbel, besides which there are other barbels attached 

 to the lower jaw, and even to the nostrils. The gill-covers want the subopercular 

 bones ; the strong, heart-shaped air-bladder adheres by its two upper lobes to a 

 bony apparatus belonging to the first vertebra. The stomach is a fleshy cul-de-sac ; 

 and the gut is long and wide, without caeca. Characters to distinguish the sub- 

 genera from each other may be found in the number and extent of the dorsal, or 

 the presence or the absence of the adipose fins, the spinous or soft structure of the 

 first dorsal ray, the form of the head, the number of barbels or their absence, the 

 nakedness of the skin, or the presence of bony plates on the head, nape, lateral 

 line, or whole of the sides, the dentition and the structure of the gills. 



In the sub-genus Pimelodus, which is very rich in species, the body is destitute 

 of lateral armature, being clothed merely with a smooth skin ; the jaws, and fre- 

 quently the palate-bones, are furnished with teeth like velvet pile, but there is no 

 band of teeth on the vomer parallel to that on the upper jaw, as in the sub-genus 

 bagrus. There is very great variety in the form of the head, and in the number of 

 barbels appended to it. The Pimelodus ccenosus inhabits Lake Huron, where it 

 frequents muddy rivers and attains the weight of several pounds. It takes a bait 

 readily and is excellent eating. A somewhat mutilated specimen, taken at Pene- 

 tanguishene, and presented to me by Mr. Todd, having been sent to Baron Cuvier, 

 was returned Avith the following remark : " Plmelode tres voisin du Silure noir de 

 Lac Erie de, La Sueur. Notre travail sur les Silures nttant pas encore termini 

 nous ri avons pas fixe son nom." This pimelode belongs to the division or tribe of 

 the sub-genus, in which there is only a single band of teeth on the upper jaw, and 

 the head furnished with eight barbels, has an oval shape, without any bony plates 

 appearing through the smooth skin. 



DESCRIPTION 

 Of a specimen from Penetanguishene. 



Form. — Profile oval, tapering into the tail. Head broadly oval, forming two-ninths of the 

 total length. Orbits small and nearer to the snout than to the gill-opening. Nostrils situ- 

 ated some distance before the eye ; a slender barbel, half an inch long, springs from their 

 posterior margin. Snout obtuse. Labials ending in a tapering barbel, which is an inch and 

 a quarter long and reaches to the gill-opening ; there are also two slender barbels on eacli 

 side of the chin. Both jaws are armed with a brush-like band of short teeth, very con- 

 spicuous in the dried specimen. The palate and vomer are smooth. The bones of the skull 

 are firmly united together, and it is difficult to distinguish the pieces of the gill- covers through 

 the skin. The upper gill-ray runs under the edge of the operculum, and is firmly joined to 



