WOOD-LICE AND SPIDERS 
191 
where this spider occurs. The silk spider is known from 
Brazil, from Central America as far north as Texas, and from 
Southern Florida. Professor Dahl* argues that the group to 
which this species belongs already had a wide range in Cre¬ 
taceous times. Its nearest relation, Nephila clavata, is pecu¬ 
liar to China and Japan. It is quite possible, therefore, that 
the American form may have existed since early Tertiary 
times. But, as Dr. Marxf observes, the spiders introduced by 
human agency have not only acclimatised themselves; they 
have also, in a more or less marked degree, driven away and 
exterminated the indigenous spider fauna. Yet among the 
remnants of that ancient fauna we recognise four species that 
are peculiar to Bermuda. Most of the remainder are identical 
with American forms. 
One of the most noteworthy animals that might he adduced 
in favour of the theory that Bermuda represents the remnant 
of a large land surface once connected with the mainland is 
the land nemertean Geonemertes agricola. This very pecu¬ 
liar worm is found in abundance at several distinct localities 
in Bermuda. It might be said that this worm is not of much 
zoogeographical value, since it is able to resist immersion in 
sea-water for some time. On the other hand, it must be re¬ 
membered that land nemerteans have an extremely discon¬ 
tinuous range on ancient land surfaces. Hence their distribu¬ 
tion is suggestive of great antiquity. Nine species of the 
genus Geonemertes are now known from Australia, New Zea¬ 
land, New Guinea, Pelew Islands, Rodriguez Island, the 
Seychelles and Bermuda. To suggest that Geonemertes 
agricola owes its presence in Bermuda to an accidental intro¬ 
duction would be quite inadmissible, because it has never 
been found elsewhere. J 
Of greater importance than any of the foregoing inverte¬ 
brates are the land and fresh-water snails inhabiting 
Bermuda. Dr. Pilsbry distinguishes autochthonous species, 
drift waifs from the West Indies, and snails imported by the 
agency of man. The last group we need not consider here, 
* Dahl, F., “ Verbreitung d. Spinnen,” p. 278. 
t Marx, G-., “ Spiders of Bermuda,” p. 100. 
\ Coe, W. R., “ Geonemertes agricola,” p. 534. 
