112 



column they are grouped under nine types, indicated by the 

 Roman letters ; and in the fourth column, under four types, 

 indicated by capitals. 



Equivalent to the ^A'hole group thus constituted is a type, 

 which appears in C. s?iturale Soivb. In the former case, the 

 group is distributed, in the various subtypes, over most of the 

 island. The latter occurs only in the western third of the 

 island, and is very uniform in its characters. 



If, following the example of some, we should regard all 

 types, which are probably original, as requiring to be named 

 and described as species, we should soon be involved in an 

 endless labyrinth. There would be not less than fifteen spe- 

 cies in this group ; the list of species of Cyclostoma inhabit- 

 ing Jamaica would be swelled to hundreds ; and the terres- 

 trial shells of that island would exceed a thousand species. 

 We prefer to treat species as we do genera, and endeavor to 

 make them of as nearly equal value as the diversified system 

 of nature will permit. We have deemed it useful to present 

 an illustration of the actual scheme of nature. 



The nine types of the third order, in the foregoing table 

 appear to be of about the mean value of ordinary species. It 

 becomes necessary to assign them names. In the absence of 

 the opercula, d and i may be omitted as doubtful. Mr. Sow- 

 erby's figure of the operculum of C. Jamaicensis accurately 

 represents that of No. 18 ; and Kiister's figure, the operculum 

 of Nos. 16 and 17 ; all of which, notwithstanding some dif- 

 ference in the opercula, we had united in one species. Most 

 of our specimens are rather too coarsely sculptured to corres- 

 pond with the figures given by these authors. Variety 16', 

 however, corresponds with great exactness to Mr. Sowerby's 

 figure. We may therefore conclude that Nos. 16-18 belong to 

 the Chemnitzian species. Our No. 1 approximates so exactly 

 to Mr. Sowerby's figure of C. corrugatum, that we shall pro- 

 yisionally refer it to that species, although Kuster's figure and 



