52 MICROSCOPICAL OBJKCTS FOUND 



The next structures contained in the Levant 

 mud to which I would direct attention, are the 

 fragments of Pinnee, and other shells. The 

 examination of shell-structures, now going on in 

 the able hands of Dr. Carpenter, has already 

 opened a new field of enquiry, and promises 

 to place in the hands of the Zoologist and 

 the Geologist, an instrument of great value, 

 applicable alike to the identification of both 

 recent and fossil shells : — one by means of 

 which many cases of doubtful aflSnity have been 

 already cleared up, and the identification of im- 

 perfect fragments rendered much easier than 

 before. Many of those in the Levant deposit, are 

 thin laminae, which have separated transversely 

 to the direction of the prisms ; but there are 

 also numbers of these calcareous prisms, which, 

 by the decay of the shell membrane, have been 

 detached from one another. They exhibit a great 

 tendency to break up in a direction parallel to 

 the transverse lines which mark the original 

 epithelial layers, producing small calcareous 

 granules, of a eemicrystalline aspect, — such as a 

 very moderate amount of cither chemical action, 

 or mechanical attrition would so modify, in 

 outward appearance, as to render the identificu- 



