182 NORTHERN ZOOLOGY. 



Teeth. — The borders of the intermaxillaries, labials, lower jaws, and palate-bones are 

 armed with very acute, slightly-curved, strong conical teeth : there is a circular cluster on the 

 knob of the vomer, a double row extending at least, half an inch backwards on that bone, and a 

 row on each side of the tongue equally strong and more curved than the others : a deep furrow 

 runs down the centre of the tongue between the rows of the teeth, and the soft parts form a 

 smooth median ridge in the roof of the mouth, without any corresponding elevation of the 

 bone. All the teeth are surrounded by soft gums, in which some small moveable teeth are 

 implanted. The following is a scheme of the dentition in the individual under examination. 



Teeth. — Intermax. 7 — 7; Labials 19 — 19; Lower Jaw 19 — 19; Tongue 8 — 8; Vomer 7 — 7*; exclusive of the 

 smaller teeth, which fall off with the soft parts. 



Gill-covers. — Preoperculum moderately curved, nearly vertical. Suboperculum deeper 

 than in the other trouts, articulated at its inner angle to the operculum and preoperculum by 

 a slender process which is concealed by these bones : its edge forms fully one-half of the free 

 border of the gill-cover and is finely grooved. The gill-rays, 12 in number, are flat, those 

 nearest the gill-cover being the broadest : seven of them are inserted into the long appophysis 

 of the hyoid bone, one or two into the intermediate cartilage, and the remainder into the 

 posterior appophysis. 



FiNs._-.Br. 11— 12f ; D. 14—0; P. 14; V. 9 ; „. 11; C. 19f. 



The dorsal fin is situated in ihe middle of the fish, the exact middle between the end of the 

 snout and tip of the central caudal ray, being opposite to the eighth dorsal ray and a little 

 anterior to the ventrals : the height of the dorsal exceeds the length of its attachment : its 

 fourth ray is the longest, the third is half as high, and is, together with the two very short 

 anterior ones, closely applied to its base. The adipose fin is small and has a club-shaped 

 profile. The ventrals contain nine rays each, the first being about twice as stout as the others. 

 The anal contains eleven rays, the first of which is one-third shorter than the second and is 

 closely applied to it : the last ray is two-thirds shorter than the second and is opposite to the 

 adipose : the space between the anal and caudal measures more than the attachment of the 

 former. 



Intestines. — (Of a male killed in Winter Lake.) Stomach a large sac continuous with 

 the oesophagus and not to be distinguished from it, bent upwards and bulging a little at the 

 bend : its inner membrane is longitudinally plaited. Caeca numerous, their insertions occu- 

 pying three inches and a half of the intestine. The internal coat of two inches of the lower 

 part of the gut is disposed in circular valvules conniventes. The air-bladder communicates 

 with the oesophagus by a tube as big as a crow-quill. In a female specimen I found a 

 number of long, slender, opake worms in the air-bladder, of a whitish colour, with a slightly- 



* The vomer is iujured, so that the exact number of its teeth cannot be ascertained, but the above number still exists 

 upon it. 



f The specimen from which the figure was taken consists of the left side of the fish only, and shows twelve gill-rays ; 

 but as that side of the membrane generally has a ray more than the right side, I have marked it as above. I noted an 

 individual which I examined at Winter Lake, lat. 64^° N., as having only eleven rays, not adverting to any difference 

 between the two sides. Dr. Mitchill's scheme of the rays of his Lake Huron specimen is as follows: — 



Eins.— Br. 13 ; D. 13—0 ; V. 9 ; A. 13 ; C. 194 or g. 



