TO GEOLOGY. 205 



Plate 6. Fig. 220. 



Description. This is rather the longer of the two ver- 

 tebrae, which probably belong to some species of fish. 

 Though somewhat different in proportions, they most 

 likely belong to the same species. 



Plate 6. Fig. 221. 



Description. This represents the spine mentioned above ; 

 a single specimen only was obtained. 



descends lower at the sides, than in the centre. The edges are perfectly 

 smooth. 



The root of the tooth is single, and remarkably large j it gradually in- 

 creases in size, from the neck downwards; it is partly hollow; its exte- 

 rior aspect is convex, in both directions. Its total length is five twen- 

 tieths of an inch, its breadth, at the base of the crown, one tenth of an 

 inch. 



2. The two vertebrae appear also to appertain to some minute species 

 of fish. They each consist of two hollow cones, united at their apices, 

 and with slender and irregular longitudinal ridges. One of them is three 

 twentieths of an inch long, and one tenth in diameter. The other is 

 one tenth of an inch long, and one tenth in diameter. 



3. The spine resembles, exceedingly, the spines found on the tail and 

 back of some of our species of Ray, (the Raia Desmarestia, Lesueur,for 

 instance). It is discoidal at base, and its point rises rather obliquely. 



I am very truly yours, &c. 



ISAAC HAYS. 

 Sansom and Eighth streets, October 1, 1833. 



