FISHES OF LAKE SUPERIOR. 263 



Lake, through Lake Erie, and Ontario, down to the St. Lawrence 

 and its outlet into the sea, into which this fish never ventures far, 

 though he does not altogether avoid brackish and salt water. 



Dr. Richardson was the first naturalist who described the northern 

 Lepidosteus. He mentions it in his Fauna Boreali-Americana, 

 under the name of Lepidosteus Huronensis, and gives a correct and 

 detailed description of it. Nevertheless, it has been since mistaken, 

 and referred to the southern species first described by Catesby and 

 Linnseus, from which it is however very distinct, both by the pro- 

 portions of its parts, its scales, its fins, and especially by the form of 

 its frontal bones, in which the supra-orbital emargmation is much 

 lower and more elongated. Again, notwithstanding the descrip- 

 tion of Dr. Richardson, Dr. Dekay has redescribed it under the 

 name of Lepidosteus Bison; and Zadock Thompson has described 

 a young specimen under the name of Lepidosteus lineatus. At 

 first, his description would seem to indicate a really distinct 

 species ; but I have ascertained, by a series of specimens, that the 

 differences pointed out are really the characters of the young, and 

 have no value as specific characters ; the detached lobe formed by 

 the upper raylets of the caudal fin is gradually united w ith the 

 lower rays,* and the longitudinal stripe, which is well marked in 

 young specimens of a few inches in length, gradually vanishes, to 

 leave only a few spots upon the sides, which even disappear entirely 

 in the oldest individuals. The vertical fins alone remain spotted in 

 the adult. The natural color of this fish is a light greenish gray, 

 passing downwards into a dull white. 



ACIPENSERID^E (Sturgeons.*) 



The family of Sturgeons is well characterized and easily distin- 

 guished from any other in the class. These fishes have generally 

 been placed in the order of Chondropterygians, near the sharks, 

 until I objected to this association, and attempted to show that, not- 



* It is a very remarkable fact that several fishes of the old Red Sandstone period 

 have, in their full-grown state, a peculiar form of their caudal fin, which is nearly 

 identical with the form of the caudal fin of the young Lepidosteus ; a form which 

 is otherwise unknown to me at present in the whole class of fishes. 



