126 NORTHERN ZOOLOGY. 



vomer by membrane which allows a free hinge-like motion. The tongue is broad and trun- 

 cated at the tip. 



Teeth. — The intermaxillaries and forepart of the lower jaw are furnished with a single 

 crowded row of small slightly-hooked teeth : on the sides of the lower jaw there is a row of 

 rather remote, long, straight, very sharp, awl-shaped teeth, implanted into the bone, with some 

 pretty large ones merely adhering to the gums. The palate bones and vomer are armed with 

 card-like bands of teeth, the interior rows on the former, and anterior one on the latter, being 

 longest : the teeth on the vomer become finer, and the band narrower, posteriorly, until it ter- 

 minates in a point opposite to the angles of the mouth. The base of the tongue, the inferior 

 and superior pharyngeal bones, and a series of small plates at the inferior union of the bran- 

 chial arches, are rough like a file with minute teeth. The branchial arches are destitute of 

 rakers, but a row of awl-shaped teeth, flanked on each side with nacry stripes of teeth, like 

 velvet-pile, crowns their acute edges. 



Gill-covers. — Preoperculum narrow, slightly curved, and carrying its breadth to its extre- 

 mities. Operculum quadrangular, four times the height of the suboperculum, which exceeds it 

 a little in length. Interoperculum almost concealed beneath the edge of the preoperculum. 

 The gill-openings are very large : the left membrane overlaps the right one at their insertion 

 into the isthmus : the rays are cylindrical, the upper one alone being flattened *. 



Fins.— Br. 15; D. 20; P. 16; V. 10; A. 18; C. 18f. Lake Huron specimen. 

 13; 22; 14; 10; 20; I8f English specimen. 



The dorsal contains twenty rays, of which the first four are short and closely applied to the 

 fifth : the fin is considerably rounded, and the length of its attachment is equal to its height. 

 The ventrals are situated midway between the tip of the snout and extremities of the caudal. 

 The anal is shaped like the dorsal, and equals it in the length of its rays, but has a shorter 

 attachment : it is opposed to the twelve posterior rays of the dorsal. The caudal is sharply 

 forked. 



Intestines. — On opening the belly the liver presents itself, having an oblong form without 

 lobes. The duct of the gall-bladder enters the intestine about an inch below the pylorus. The 

 stomach is a straight tube, plicated internally and capable of great distention : its muscular 

 coat is strong, and several longitudinal bands of fat and blood-vessels are continued from its 

 peritoneal coat along the rest of the intestine. Below the pylorus, which is much contracted, 

 the intestine gradually diminishes in calibre and in the strength of its coats : but the rectum is 

 a little wider. A cordiform spleen is attached to the stomach. A large air-bladder extends 

 the whole length of the abdomen : it has a tendinous capsule to which it adheres but slightly. 

 The kidneys, of a wax-yellow colour, speckled with black, extend along the spine from the 

 gullet to an inch beyond the anus : the urinary bladder is separated from the kidney by the 

 lower end of the air-bladder. 



* One of our English specimens has 1'2 gill-rays, another has 13, and a third has 13 on one side and 14 on the other. 



