FAMILY SILURID^E PIMELODUS. 183 



wide, with eight branchial rays, the last almost rudimentary. Two blunt spines on the hu- 

 meral bone. Upper jaw longest ; both with a band of numerous, small, crowded teeth. A 

 roughened orbicular patch on each upper pharyngeal. 



The first dorsal fin commences at about one-third of the total length, higher than long, 

 rounded above ; the first ray stoutly spinous, the fourth longest. Second dorsal adipose, 

 elongated, and placed above the termination of the anal. Pectorals small, with a serrated 

 spine, and nine closely crowded articulated rays. This spine, like that of the dorsal, by an 

 ingenious mechanism, becomes fixed and immovable at the will of the animal, and serves as 

 an important arm of defence. The ventrals smaller than the pectorals, placed beneath the 

 last ray of the dorsal, and with eight rays. Anal long and subequal ; its first rays short, and 

 partially concealed. Caudal nearly even, slightly rounded. The intestines simple, and with- 

 out caeca. Vent oblong. Kidneys very large, surround the base of the air-bladder, and ter- 

 minate in a large urinary bladder. Air-bladder oval or heart-shaped, and apparently simple ; 

 but when the external white fibrous coat is removed, it is found to be covered with a thin trans- 

 parent membrane forming two distinct sacs, lying side by side ; and each sac is again stran- 

 gulated towards its anterior extremity, thus forming four distinct cavities. 



Color. Dusky, with a deeper shade on the back and summit of the head. Sides of the 

 head with a greenish tint ; cupreous on the sides. Abdomen pearl-grey. Fins dusky. After 

 death, from infiltration, some of the fins become tinged with red. Irides white. 



Length, 7*5. 



Fin rays, D. 1 .6 ; P. 1 .8 ; V. 8 ; A. 23 ; C. 19. 



This is one of our most common species, and makes its appearance in market in the first 

 days of April. A peculiarity connected with this species, and perhaps with others of the same 

 family, is, that it occasionally appears without any ventral fins. I have seen two thus de- 

 prived of these fins, and this furnished a naturalist with an opportunity of forming a new genus 

 Pimapterus. The specimens thus defective agreed in every respect to the minutest particular 

 with the species above described, so that I am induced to conclude that it was entirely acci- 

 dental. May not the genus Astroblepus of Humboldt (Obs. Zool. Vol. 1, p. 19, pi. 7), be 

 founded on a similar mal-formation ? We notice that Cuvier passed over this genus in silence 

 in the last edition of his Regne Animal, although M. Valenciennes has reproduced it in his 

 continuation of the Histoire Naturelle des Poissons. 



The Common Catfish, Horn Pout or Minister, has a wide geographic range. It occurs in 

 the great lakes, and along the Atlantic States from New-Hampshire to Florida. 



