SNAILS OF BERMUDA 
193 
represents a relict of early Tertiary times. The ancestors of 
Iielicina 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. Recently 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 only chasing an “ ignis fatuus.” Dr. 
Pilsbry J 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,” Yol. IX., p. 56. 
+ Boettger, O., “ Helix-Arten aus d. Tertiar Europas,” p. 103. 
f Pilsbry, H. A., “ Mollusks of Bermuda,” pp. 491—509. 
§ Gulick, A., “ Fossil Land Shells of Bermuda.” 
L.A. 
O 
