194 Value of the Shells of Mollusca for the pupose 



species are the effects of locality : that the types which are 

 exactly of a specific value were created in one centre in a 

 single stock ; (although, as we have seen, the notion, that all 

 animals can be referred to species which are of precisely the 

 same value, is wholly fanciful) ; but that those types which 

 are more comprehensive than species had a plural origin of 

 exactly as many stocks as they contain good species ! and 

 that species of doubtful value would not be doubtful, if we 

 looked at nature through the doctrine of the logical infimaB 

 species ! 



Notice of a Reversed Cyclostoma. 



In the extensive genus Cyclostoma, only one reversed spe- 

 cimen, so far as we can learn, has hitherto been known to 

 Conchologists. It belongs to the small European species C. 

 scalarinum Axilla, and is in the collection of Dr. L. Pfeiffer. 



Among the multitude of shells of the Cyclostomidse, which 

 have been accumulating for ages in Jamaica, I was unable to 

 find one reversed specimen. Recently, however, the Rev. F. 

 R. Holland has sent me from Jamaica a reversed specimen of 

 C. Jayanum. The shell has attained nearly its full size, 

 being 0.7 inch, long, but it wants the reflected lip of matu- 

 rity. This species is one of the most abundant in the island. 



From the Proceedings of the American Association for the Promotion of Science. Aug., 1850. 



On the Value of the Shells of Mollusca for the purpose of 



distinguishing Species and Higher Groups. By C. B. 



Adams, November, 1851. 



The following remarks contain little or nothing that is 



new; on the contrary, their object will require allusion to 



very familiar facts. For this, I hope that a sufficient apology 



