not been united, but tbat it has been connected by interposed mem- 

 brane. This part happens, fortunately, to be in so good a state of preser- 

 vation, as to allow the several osseous parts of this plate to be distinctly 

 made out. At .#, is seen a part of the anterior appendix; at b, is the 

 anterior branch; ate, the posterior branch; and at d, is the posterior 

 appendix. rq 



In Verona, and chiefly in the Valley of Ronca, fragments of tortoise- 

 shell are found; and, from the rugous state of the outer surface of some 

 of these, I have little doubt of their having belonged to some of these 

 animals, whose coverings were partly coriaceous; for in these, although 

 the outer surface of their covering would be smooth whilst living, they 

 would be thus rugous after the death of the animal. 



Mr. Johnson, of Bristol, was lately so fortunate as to find, at the Old 

 Passage, in Gloucestershire, some fossils of a very curious appearance and 

 form. One of these is represented Plate XVIII. Fig. 1. This, with 

 several others, most of which are much larger and possess a fine polish,, 

 and are of a deep black, I conceive to be the digitated terminations of 

 the sternal plate belonging to one of these animals, with a partly mem- 

 braneous or coriaceous covering. These fossils approach the nearest to 

 the corresponding parts in the Trionyx carinatus of M. Geoffroy St. Hi- 

 laire. One of the fossils found by Mr. Johnson is decidedly the osseous 

 plate belonging to the posterior appendix, and resembles very much, in 

 its form and rugous surface, the corresponding part in Trionyx Mgyp- 

 tiacus, of M. Geoffroy St. Hilaire, but is full six times as large. 



I must not conceal from you, that the ingenious gentleman who pos- 

 sesses these fossils is disposed to entertain a different opinion, and to 

 believe that they are the parts of the jaw or palate of some 'fish. This 

 must remain to be determined by some more illustrative and analogous 

 ^pecimen : until then, I shall hold my opinion with diffidence ; for, as I . 

 have had already occasion to notice, error in these inquiries are very, 

 easily fallen into. Thus has Faujas St. Fond, in the elegant work where 

 he has displayed so many remains of these animals, mistaken the shoulder- 



