I so SPECIFIC DESCRIPTION. 



tered 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 po- 

 sitions, 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 arti- 

 ficially distended. There is no visible communi- 

 cation 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 muscu- 

 lar 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 

 ludden. The two species porustis and larvcpforml^ 

 arc however obviously of the same genus. 



