SNAILS OF BERMUDA 193 



represents a relict of early Tertiary times. The ancestors of 

 Helicina convexa, which is peculiar to Bermuda, reached the 

 island presumably in the Oligocene Period, when we know 

 that the genus inhabited the island of Florida. 



Thysanophora is a member of the large family of Helicidae. 

 It is most characteristic of the West Indian region and Central 

 America, and Dr. Pilsbry * declares that it represents the 

 oldest stock of the West Indian Helix fauna. The ancestors 

 of Thysanophora hypolepta may well have wandered to the 

 Bermudan area from the West Indian region in early Tertiary 

 times. This suggestion is strengthened by the fact that along 

 with Succinea and Poecilozonites it is found fossil in the 

 " red earth." The genus Poecilozonites, with its four 

 Bermudan species, is peculiar to Bermuda. Eecently Pro- 

 fessor Boettger f again drew attention to the intimate rela- 

 tionship existing between this genus and the German lower 

 Miocene Helix imbricata, in spite of Dr. Pilsbry's plea that 

 the German savant was oqly chasing an " ignis fatuus." Dr. 

 Pilsbry $ prefers to derive Poecilozonites from an old 

 American stock, arguing that it is related to Gastrodonta. To 

 trace the exact affinity of a recent to a fossil form is always 

 a matter of considerable difficulty, but since several other 

 European palaeontologists have dwelt upon. the remarkable 

 and undoubted relationship existing between the present West 

 Indian fauna and the fauna of the European early Tertiary 

 deposits, and as I shall be able to bring forward additional 

 evidence in favour of their views, I am certainly on Professor 

 Boettger's side in this controversy. That Poecilozonites is 

 not a recent arrival from elsewhere, quite apart from the fact 

 that it is unknown outside the Bermudan area, is likewise 

 indicated by its fossil occurrence in the red earth, which 

 is held to be of Miocene or Pliocene age. Dr. Gulick records 

 eleven species and sub-species of Poecilozonites from the red 

 earth, as well as Succinea bermudensis and a number of 

 genera that have since become extinct. 



* Pilsbry, H. A., " Manual of Conchology," Vol. IX., p. 56. 

 t Boettger, O., " Helix- Arten aus d. Tertiar Europas," p. 103. 

 t Pilsbry, H. A., "Mollusks of Bermuda," pp. 491509. 

 Gulick, A., " Fossil Land Shells of Bermuda." 

 L.A. 



