180 SPECIFIC DESCRIPTION. 



scattered hairs. The disconnected valves are 

 placed at the precise distance at which they were 

 situated from each other when they were detached 

 from the animal, which is preserved in spirits. 



The dried specimen, which is figured in two 

 positions, is probably much contracted, as three of 

 the valves are imbricated : this shows, also, the 

 portion of the shell which is exposed, about one 

 third of each valve. The pores exist in this as well 

 as the preceding species, but are much smaller, 

 and scarcely discernible except when they are 

 artificially distended. There is no visible commu- 

 nication between the external perforations and the 

 lungs ; it is not easy therefore to determine their 

 use or functions. The fact of the valves not being 

 at all times approximate, will scarcely prevent this 

 species from being justly ranked in the genus 

 Chiton, as the valves are constructed so as to lie 

 partially one over the other, and from the muscular 

 contraction of the animal are doubtless often so 

 arranged. But it can hardly be denominated Cryp- 

 toconchus, as a considerable part of the shell is not 

 hidden. The two species porosus and larvceformis 

 are however obviously of the same genus. 





