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LETTER XVI*. 



ENTOMOLITHI INSECTS IN PAPPENHEIM LIMESTONE IN COAL 



SLATE CRABS OF SI1EPEY, VERONA, EAST-INDIES, AND MAES- 



T RIGHT ONISCITES MONOCULITES TRILOBITES. 



1 HE extreme softness of the parts, and the general delicacy of struc- 

 ture, which exist in the smaller insects, will easily explain the circum- 

 stance of their being rarely met with in a mineralized .state. Very few 

 indeed are the instances which I shall be able to adduce of Entomolithi, 

 or of the mineralized remains of this class of animals. 



The specimen represented Plate XVII. Fig. 2, is a slab of the fissile 

 cream-coloured lime-stone from Pappenheim, in which the traces of an 

 insect are sufficiently plain to mark its presence, without, however, being 

 sufficiently distinct, to point out the genus in which it should be placed. 



The head of the animal is plainly to be seen, but none of its parts are 

 distinguishable. It appears to have been connected with the thorax by 

 a contractile neck ; since, in another specimen, apparently of the same 

 species, the neck appears to be as long as the thorax ; whilst, in the spe- 

 cimen here depicted, the distance between the head and the thorax is 

 very small. The thorax appears to have been nearly cylindrical, and 

 much shorter and wider than the abdomen, which is of a lanceolated 

 form, and is evidently composed of about eight articulated rings. In 

 one of M. Knorr's figures, PI. xxxni. the tail of this animal terminates 



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