236 UPPER, OR FLINTY CHALK. 



it contains some traces of the tail; but no vestige of the other fins 

 remains. 



Tab. xxxiii. fig. 12, represents the head of this ichthyohte; it exposes 

 ihejaws, part of the gills, temporal bones, &c. , 



The specimens here figured, present but little information concerning 

 the structure of the original; and it is but very lately, that the discovery 

 of a most interesting example, has enabled me to determine its characters 

 with precision. In the fossil alluded to, the back of the animal is im- 

 bedded in the chalk, but the abdomen, head, &c. are distinctly exposed. 

 This fish lies three inches in relief, is nine inches long, 2-5 inches wide 

 between the pectoral fins, and one inch between the ventral; the latter 

 being placed three inches below the former. The relative situation of 

 these parts may probably have been altered by compression, but the spe- 

 cimen is so httle distorted, that the difference produced by this cause 

 cannot be material. The head is considerably mutilated ; it exhibits por- 

 tions of the jaws, temporal bones, the plates of the opercula, and ten or 

 eleven branchiostegous rays on each side ; the latter are spread ovit from 

 beneath the opercula, and meet under the lower jaw. Both the pectoral 

 fins are preserved; the right one remains in its natural situation; thfe 

 other is displaced, and partly covered by the gills; each is composed 

 of seven or eight rays. The ventral fins consist of six or seven rays, and 

 are partially separated from the body of the fish. The number, form, 

 and situation of the dorsal fins, cannot be ascertained without removing a 

 considerable portion of the chalk, and incurring the risk of injuring the 

 specimen. The tail is altogether wanting. 



This magnificent fossil fish, (probably one of the most interesting 

 Great Britain has produced, was discovered too late for representation in 

 the present volume. 



Locality. Lower chalk, near Lewes. 



115. Detached scales of fishes. Tab. xxxiv. figs. 1, 2, 3. 5, 6. 



With the exception of fig. 6, which evidently belongs to the Salmo 

 Lewesiensis, the scales here delineated, cannot with certainty be referred to, 

 any known species. 



