276 LAKE SUPERIOR. 



The only specimen of this species which is in my possession 

 was found at Michipicotin on the north-east shore of Lake Superior. 



Though this species is very similar in its general characters to 

 the Acipenser macidosus Lesueur, from the Ohio, we have not, 

 however, been able to identify it. The description which this au- 

 thor gives of his species is so vague that he does not even tell 

 us the form of the fins. The formula of their rays is far from 

 corresponding with that of our species. Nor is the abdominal sei'ies 

 of plates the same ; those of the sides and back seem to resemble 

 it more closely. The snout is also more slender; but had not 

 Lesueur mentioned that the species which he saw is of small size, 

 we might have supposed that our specimen was the young, which 

 have generally the snout more pointed than full-grown specimens. 



Acipenser rhynch^us, Agass. 



This species is very similar to the preceding ; it differs from 

 it only in a few characters which we shall here enumerate briefly. 

 The bod}^ is more slender and diminishes less abruptly towards 

 the caudal region. The curve of the back is more elliptical; 

 slightly concave at a small distance behind the head, where the 

 third escutcheon is sensibly smaller. The head is contained about 

 four times in the whole length. The face, from the anterior 

 margin of the branchial cavity, forms the fifth part of the length 

 of the trunk, and the snout from the nostrils is in the propor- 

 tions of one to five. The whole length of the fish is nearly twenty- 

 three inches. The head is slender, elongated, proportionally nar- 

 row ; its upper surface is very sloping, forming a line feebly broken 

 at the level of the nostrils. A sinus quite deep, widened on 

 both sides, extends along the median line of the skull ; narrow 

 at the top, it widens before it disappears upon the snout. The 

 frontal and parietal bones are carinated in their middle. The 

 snout is pointed, but truncated. It is completely covered with 

 small plates which pass before the nostrils and go to join again 

 the bone which terminates the lower and posterior angle of the 

 face. The nostrils open in a bare space which is situated under 



