238 NORTHERN ZOOLOGY. 



longed behind the cranium, master animals capable of making strong efforts to 

 escape. A specimen of the Northern Mailed-fish, which was prepared for me by 

 Mr. Todd, at Penetanguishene, having been sent to Cuvier, was returned with the 

 following remark, " Esox osseus, Linn. Lepisosteus rostratus, Nob. ;" but M. 

 Agassiz, who has studied this genus of fishes with great diligence, in connexion 

 with the closely-allied fossil tribes, is of opinion that the Lake Huron Lepisosteus 

 is a distinct species from the more southern one described by Linnseus, and Mr. 

 Gray has kindly supplied me with a note of the specific peculiarities which he drew 

 up at M. Agassiz's request. 



DESCRIPTION 

 Of a dried specimen from Penetanguishene, on Lake Huron. 



Form. — Body elongated, roundish, fusiform, slightly flattened on the back, belly, and sides ; 

 deepest at the ventrals, where its vertical diameter exceeds its thickness by about a ninth 

 part. In profile the back is slightly arched. Head four-sided, its breadth greater by one- 

 third than the height of the gill-covers : it is even and flat above and on the sides, which 

 taper gradually into a narrow beak, more than twice the length of the rest of the head. The 

 whole surface of the head and bill is bony, finely furrowed and granulated, except the gill- 

 membrane, and its prolongation forwards between the limbs of the lower jaw: the sutures of 

 the bones are very evident. Orbits circular, situated close to the articulation of the lower 

 jaw, and thrice their own diameter from the edge of the gill-plates. Nostrils close to the end 

 of the bill, the posterior orifices on the dorsal aspect, the anterior ones lateral. Cheeks 

 altogether behind the orbit, covered by about twenty polygonal plates, resembling the rest of 

 the surface of the head, and concealing the preoperculum and infra-orbitar bones. Edge of 

 the gill-cover semi-oval : suboperculum and operculum nearly of equal size : interoperculum 

 larger than either and nearly as broad. Bill flat, or very slightly rounded on its upper sur- 

 face, which is formed by the ethmoid bone bordered on each side by the long narrow labials, 

 the blunt tip being composed of the small intermaxillaries that are attached to the end of 

 these bones. The under jaw equals the labials in length, and its rounded tip shuts in behind 

 the intermaxillaries, so that even the nostrils project beyond the mouth : the posterior limbs 

 of the lower jaw expand vertically, rising nearly as high as the upper margin of the orbit. 

 Tongue long and narrow, regularly wrinkled transversely with a median line in the dried spe- 

 cimen. 



Teeth. — There are two contiguous rows of straight, subulate, very acute teeth on the 

 labials, intermaxillaries, and under jaw : those composing the outer row being unequal in size, 

 though small and densely crowded ; the interior ones are distant, and all about two lines long. 

 The vomer, palate-bones, and inner surface of the lower jaw are covered by multitudes of 

 very minute teeth, which are bounded on each side by an even row a little taller than the 

 others. 



Scales. — The body is covered with strong thick scales, which look as if composed of enamel, 

 but are not quite so hard, as they yield slightly to the knife. They are thickened in the 



