*261 



tie prospect of success can exist in attempting to make a distinction be- 

 tween them. 



I am entirely unable to say any thing with respect to the specific 

 distinctions of any of the crabs which I possess. Mr. Francis Crow, of 

 Faversham, is of opinion, that he possesses about twelve different fossil 

 crabs, from Shepey ; and, in the collection of the London Museum, there 

 existed, in the opinion of its learned possessor, more than three times as 

 many; none of which he finds exactly agrees with any in his extensive 

 recent collection. 



Plate XVII. Fig. 1 and 7, represent two different specimens of fossil 

 crabs from the Isle of Shepey, distinguishable from each other by the 

 markings on the dorsal plate. Crabs, apparently similar to those which 

 are found at Shepey, are also obtained from the neighbourhood of Ve- 

 rona. Very fine fossil remains of this kind are also found, in Malta, ,as 

 well as in Anjou, in the department of Maine and Loire. 



Fossil remains of lobsters are sometimes found, in very good preserva- 

 tion, in the Isle of Shepey. 



We learn from M. Knorr, Monum. des Catast. T. i. p. 19, that the fos- 

 sil remains of river animals of this genus, the cray-fish (astaci), are found 

 in no other part of the world, but in a narrow district, reaching from 

 Gunzenhausen, in Anspach, to Aichstaedt, a length of about seven or 

 eight leagues, bordered on one side by the river Altmuhl, which, he 

 observes, abounds with animals of the same kind. 



The matrix of these petrifactions is a fine light yellow limestone, 

 which frequently separates in tables, by which the contained fossils are 

 beautifully displayed. These animals appear to have been imbedded in 

 their matrix during the precipitation of the calcareous particles from the 

 fluid in which they had been held. A fossil shrimp, from these quarries, 

 is shown Plate XVII, Fig. 8. 



Plate XVII. Fig. 12, is the representation of a fossil crab, from the 

 East Indies. These fossils are known by the name of Ceylon crabs; 



