238 UPPER, OR FLINTY CHALK. 



rather channelled in front (vide fig. 2, Tab. xh.). The teeth on the left 

 side (the uppermost row in the figure,) ai-e of various sizes, the two pos- 

 terior ones being very short ; they are not attached to the edge of the jaw, 

 but to a longitudinal depression on its inner surface. The teeth on the 

 right side are very irregularly disposed, and appear to have suffered some 

 degree of displacement; four of them, including the anterior tooth, are 

 affixed to the margin of the jaw, but the penultimate one is placed nearly 

 0-3 inch within the outer edge*. 



Tab. xh. fig. 1, the lower jaw above described. 



fig. 2. Front view of the anterior teeth of the same. 



Tab. XXV. fig. IS. Lower jaw oi I^sox Lewesiensis in a young state. 



Tab. xxxiii. figs. 2, 3, 4. Detached teeth of the same. 



Localities. Upper, and Lower chalk, near Lewes. 



The ichthyolite we have next to describe, is in all probability abdo- 

 minal, but the situation of the fins is so imperfectly shewn, that even tliis 

 point cannot be positively ascertained. The determination of its generic 

 characters is involved in stiU greater obscurity, since there does not appear 

 to be any recent genus to which it can be correctly appropriated. It 

 bears some affinity to the Antherina, Mugil, and Polymnemus, but possesses 

 characters obviously distinct from either of those genera. In the elon- 

 gated form of the body, the number and situation of the fins, and in the 

 dentature of the jaws, it resembles an ich thy ohte figured by Cuvierf ; and 

 which is considered by that illustrious naturalist, as approaching to the 

 Amia calva\ of Linne. 



Both the fossils in question differ however from each other, and from 

 the recent species, in many important particulars; and although it is 

 probable they wiU hereafter be found to be but very remotely related, yet 

 in the present infancy of oryctological science, it may be excusable to 



* Whether this is the result of accident or of original conformation, cannot perhaps be 

 determined. It is not however improbable, that the original may have been provided with 

 two sets of teeth in each maxilla, the outer row being attached to the margin of the jaw, and 

 the inner set, to a depression on the inner surface ; the teeth of the latter, being placed opposite 

 to the intervals left between those of the former. 



■\ Fossiles de Paris; lieptiles et Poissons, fig. 13. 



% The Amia calva is a fresh water fish, inhabiting the rivers of Carolina. 



