of distinguishing Species and Higher Groups. 203 



a value similar to that of the skeletons of Vertebrata, but 

 admit the amount of the value to be less, on account of the 

 greater simplicity of shells. 



It is, therefore, true that a collrction of the shells of Mol- 

 lufeca corresponds to a collection of both the stufted skins and 

 the skeletons of Vertebrata, but is of inferior value, both for 

 the reasons just mentioned and because their presence is not 

 universal in their department. 



It is perhaps unnecessary to add that while we believe 

 that the shells of Mollusca are sutficient for distinguishing 

 species, we would not regard them as alone the basis of species. 

 This would be an artificial method, although in the results it 

 would coincide with the natural method of classification. But 

 the shells are partly the basis of, and partly the index to; spe- 

 cific characters. 



The following errata in the catalogue of the land and fresh- 

 water shells of Jamaica (pp. 179-187) have been detected : — 



No. 34, Cyclostoma Neivcombianum, Ad., raay be erased 

 from the catalogue. Since the remark on p. 177, it has been 

 proved to belong to the Island of St. Thomas. I am indebted 

 to the kindness of a friend for an extensive suite of varieties of 

 this species, which he collected in that island. The most com- 

 mon variety is that which has been known in many collections 

 as C. Swiftianum. This name was derived from the MSS. 

 of Dr. W. Newcomb, now of Honolulu in the Sandwich Islands, 

 and was given to the species in honor of Robert Swift, Esq., of 

 St. Thomas, k. red variety has been described in the Zeitschrift 

 fur Malakazoologie, subsequently to our description, by Dr. 

 Pfeiffer, as C. Troscheli. The synonomy therefore will stand 

 thus: 



(Cyclostoma Swiftianum Newcomb MSS., 1845.) 



Newcombianum'Ad. Cont. Conch. Sept., 1849. 



Troscheli Pfr., Zeitschr., June, 1850. 



