412 PROCEEDINGS OF THE ACADEMY OF [April, 



Pcecilozonitcs reinianus than are now living. The largest specimens 

 even of Pcecilozonites circumfirmatus and Succinea hermudensis are 

 among the fossils. These snails must have found more food than there 

 is now on the uncultivated ground. There is also geologic evidence 

 that they belonged to a more prosperous epoch than the present. Prof. 

 Heilprin reports that in excavations for one of the docks, specimens 

 of Pcecilozonites nelsoni were brought up from a peat deposit at a depth 

 of forty feet below water. A rise of the land sufficient to put these 

 shells ten feet above sea-level (see Map No. 1) would multiply the land 

 area eight or ten times, changing it from a narrow ridge, hardly two 

 miles wide at its widest, into an elliptical area, including, it is true, some 

 large lagoons, but in all about ten miles across and more than twenty 

 miles long. A large, protected interior valley w^ould then receive the 

 fertile soil that is now washed into the lagoon by every storm. It 

 would not surprise me if the deposits at locality 807 should be shown 

 to date from the period of this Greater Bermuda, but a person need 

 hardly wait for this proof before supposing that the indigenous con- 

 temporaries of Pcecilozonites nelsoni were also characteristic of Greater 

 Bermuda. 



In spite of their e\ddent prosperity, I do not think it could be proved 

 that these snails lived under any densely shading vegetation. The 

 humidity at Bermuda makes such a shade less necessary for snails 

 than it is in many places. I have often seen Succinea hermudensis 

 clinging to grass and to trunks of trees in such situations that I imagine 

 an American summer day would have desiccated them. The tract 

 about Prospect Hill (No. 809) must have been desolate, unshaded land 

 when the hills were growing dunes, yet the sand here (localities 808 

 and 809) contains numerous well-developed specimens and quite a 

 variety of species. These must either have lived where they are found, 

 or else have been blown there from some place almost equally wind- 

 swept. 



The extinction of species that were able to prosper on those barren 

 parts of the island seems to me a strange occurrence. If, as I l^elieve 

 is probable, the sand for these dunes came from near the present north 

 shore, then the island must have had very nearly its present shape 

 and size when these snails were alive. Thus when the Greater Bermuda 

 sank, the change seems to have set new dunes in motion across this 

 section of the Lesser Bermuda; and Pcecilozonites zonatus, Cary- 

 chium hermudense and Euconulus turhinatus not merely survived the 

 subsidence, but even formed a considerable population on the parts of 

 the remaining island that were most damaged by the changing condi- 



