MR. GRAY ON THE STRUCTURE OF CHITONS. 
145 
5. The valves of these shells, instead of being- simply placed on the surface of the 
mantle and attached to the animal by muscles, are inserted by their edg-e into the 
substance of the cartilaginous mantle. 
Hence we may conclude, that though it is impossible to adopt M. de Blainville’s 
views with regard to the systematic arrangement of Chitons, yet they offer many 
particulars not found in other rnollusca ; and that in the structure of the edge of 
the valves, where they are inserted into the mantle, and in the formation of the central 
cellular coat, which is doubtless formed by small processes of the mantle, like the 
tubes in the substance of the valves of the coronal Cirri pedes, they offer an analogy 
to the shells of those Crustacea which has not before been observed. 
MDCCCXLVIII. 
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