On fJie Flora and Fauna of Santa Cruz. 121 



the plants in common to all the islands, as well as to the West 

 Indies and the continent, have expanded themselves over their 

 present geographical areas, at least iis far as they are not pos- 

 sessed of particular faculties for emigration over the sea. By a 

 snbsecpient volcanic revolution, St. Croix, as well as many of the 

 other islands, has thereafter been separated from Porto Eico 

 and the Virgin Islands, and put into its present isolated posi- 

 tion, which it seems to have retained ever since, whilst the latter 

 group of islands litis either still, for a long period, remained in 

 connection with Porto Eico, or, if separated at the same time 

 from it as St. Croix, has, by another revolution, been again con- 

 nected with the former.'' 



As to the plants now living in Santa Cruz, which have not 

 been found in the Virgin Islands, Baroa Eggers desires it to be 

 understood, that whilst his investigations of Santa Cruz have 

 been thorough, his explorations have been less complete, and he 

 feels confident that not a few of such i^lants may, by closer re- 

 search, still be discovered in the latter. 



I propose, now, to examine the character of the terrestrial 

 mollusca of Santa Crnz, and the evidence which they offer as 

 to the connection of that island with others in its vicinity. 



The most important feature is the nnmber of species found 

 semi-fossil only, — several extinct, others still living elsewhere : 

 of the whole, I add the following list. 



Semi-fossil species, extixct. 



? Clioridropoma dasicarinatunu Pfr. 

 '•' clwrdiferum, '* 



The latter, perhaps, a variety of the former. 



C. Santacruzejise, Pfr., now living in Santa Cruz and St. 

 Thomas, is of much the same type, and may be considered the 

 living representative of C. iasicarinatum. 



In Malac. Blatt., xxi, p. 173, D. P. Weinland described a 

 fossil, from Menk.e's collection, attributed to Hayti, as Cydostoma 

 (Tudora?) Kazika. He sent to me a specimen of it, and I 

 forwarded to him the Santa Cruz fossil ( C. hasicarinatum), which 

 he considers the same, the habitat Hayti of Menke being erro- 

 neous (Jalirb., vii, 1880). 



