1 90 SPECIFIC 



The animal possessing this very curious multl- 

 valve shell differs from the inhabitant of Chiton 

 in the arrangement of the lungs, which do not ex- 

 tend so far on either side, but only about one third 

 of the length; and in the intestinal canal. Tiiis 

 dissimilarity in the worm will not however be a 

 sufficient ground for separating it from the firnt 

 Linnsean genus. Nor will the extension of the 

 membrane over the whole surface exclude it ; for 

 a regular gradation through the next species and 

 C. tunica t us may be traced from this to any indi- 

 viduals of the genus which are perfectly un- 

 covered. 



The specimen figured in the plate and the fol- 

 lowing one are both deposited in the British Mu- 

 seum. They have been examined by Dr. Blain- 

 ville of Paris, by whom a communication respect- 

 ing them has, it is understood, been made to the 

 French Philomatic Society. The names he has 

 affixed to the two species are Cryptoconchus po- 

 Tosus, and C. larvcejormis. 



To the politeness of Dr. Leach, of the British 

 Museum, the author owes his opportunity of ma- 

 king the annexed drawings, and of inspecting the 

 mollusca. 



