186 NEW-yORK FAUNA. 



that they know of none in the rivers of the two Americas. On account of its dorsal spine, it 

 cannot be admitted into that genus ; and the same spine being smooth, and not serrated, 

 excludes it from Schilbe. Its natural position in a general arrangement of the Silurids would 

 seem to be between Schilbe and Cetopsis ; forming a passage, by its simply spinous anterior 

 dorsal and pectoral ray, from one to the other. It may be thus characterized : " No adipose 

 fin ; simple spines to the dorsal and pectoral : anal long ; caudal pointed, not united to the 

 anal." Important details respecting the teetli are wanting to complete the character. I sub- 

 join the description : 



" Long-tailed Silurus. Silurus gyrinus. Without an adipose fin ; without a second 

 dorsal fin ; and with a lengthened tail, resembling that of the common tadpole. Brought by 

 Dr. B. A. Akerly from the Walkill, where the species is numerous, and an individual seldom 

 equals the length of four inches. His general figure is that of a broad head horizontally 

 extended ; of a thin tail perpendicularly flattened, and of a belly giving him a roundish appear- 

 ance towards the middle of the body. There are four cirri beneath the chin, two in the upper 

 jaw, and two larger ones at the corners of the mouth. The gape is wide ; mouth large ; lips 

 fortified with a row of small teeth ; tongue broad, distinct. There is but a single dorsal fin, 

 and that consists of seven rays, of which the first is spinous. About an inch behind it, com- 

 mences the caudal fin, which is continued cpiite round the tail, and almost to the anal fin. 

 The form is lanceolate and pointed ; and the rays are so flexible and delicate, that in the spe- 

 cimen now before me, the caudal fin puts me in mind of a brush. It may be compared to the 

 tail of an eel ; the resemblance is nearer to that of a tadpole, when it approaches the period 

 of conversion to a frog. The vent is nearly midway of the body. The anal fin, consisting 

 of about sixteen rays, is situated between it and the caudal ; for though the caudal is con- 

 tinued almost to it, there is no union. The pectoral fins have seven rays, of which the fore- 

 most is spinous. The spines of the several fins, though sharp, are not serrated. I could not 

 discover any barbed or jagged configuration whatever in either of them. The abdominal fins 

 are small, approximated, and almost as far back as the vent. The lateral line, after passing 

 the thoracic parts, passes along to the middle of the tail, liaving the appearance of a dark stripe. 

 The tail exliibits other faint marks of lines or stripes, while the trunk and head have a sort of 

 mottled or clouded appearance. The belly is whitish or cream-colored. 



" The want of serrae to the spines, and of a second dorsal fin, might lead some to remove 

 this fish from the Silure family ; but to avoid needless innovation, I retain him iiere." 



{E^^TRALIMITAL.) 



P. canosus. (Richardson, F. B. A. Vol 3, p. 132.) Barbels at the angle of the mouth, not reach- 

 ing the gills. Br. rays 9. The pectoral spine strongly serrated. Caudal rounded. D. 1.7.0; 

 P. 1.8; V. 8; A. 24; C. 17 Jj. Length ten inches. Lake Huron. 



P. albidus. (Lesueur, Mem. Mas. Vol. 5, p. 148.) Whitish ash. D. 1.6; P. 1. 10; V. 8; A. 22; 

 C. 10; Length 12 to 15 inches. Ddaware. 



