UPPER, OR FLINTY CHALK. 239 



retain thera under the same genus, until their characters shall be accu- 

 rately determined, by the discovery of more illustrative specimens. 



117. Amia? Lewesiensis. Tab. xxxvii. xxxviii. 



The length of this ichthyolite generally exceeds eighteen inches, the 

 head being equal to one-third of the whole; the width is about 4-5 inches. 

 The body is of an elongated form, sHghtly compressed, scaly, and reti- 

 culated. 



The scales are of a rhomboidal shape, and beset with numerous, small, 

 adpressed spines, producing a scabrous reticulated appearance, not unlike 

 the surface of some kinds of BaUstes. The head is angulated ; the orbits 

 large; the opercula smooth, and rounded; the jaws dentated, and nearly 

 straight. The teeth in the upper maxilla are conical, pointed, and rather 

 fiat; there are about forty on each side, of which the eight or nine anterior 

 ones, are the largest. Those of the lower jaw are exceedingly smaU, and 

 very numerous. The dorsal fins are two in number; the anterior one 

 {a. Tab. xxxvii.) is placed in a sulcus, or groove, in the back, and appears 

 to have been capable of erection or depression ; it consists of eight strong 

 rays, the two first being garnished mth spines. The posterior dorsal fin 

 {b. Tab. xxxvii.) is remote from the other, and composed of numerous 

 dehcate rays. The pectoral fins are placed on the thorax, near the lower 

 margin of the opercula. The ventral fins (c. Tab. xxxvii.) are attached 

 to the abdomen, opposite to the anterior dorsal fin. The anal fin is un- 

 known. The tail appears to have been rounded, but no perfect specimen 

 of this part has been obtained. The tongue is occasionally preserved, 

 (vide Tab. xxix. fig. 6. Tab. xxxiv. fig. 7.) It is of a triangular form, 

 and its surface is covered with numerous papillae. The air bladder is of 

 an elongated oval shape, and hes in the abdomen, immediately beneath 

 the spine*. 



From the preceding description, which comprehends all that is at 

 present known concerning this curious ichthyolite, the original appears to 



* It may seem scarcely credible, that a part of such delicate structure, should be preserved 

 in a mineralized state, yet the fact is unquestionable ; I have three specimens in my collection, 

 in which it is clearly shewn. 



