114 
PACIFIC SCIENCE, Vol. XIII, April, 1959 
recorded from the United States. Shoemaker 
(1936) has noted it from Louisiana, and from 
Balboa Park, San Diego, and Pasadena, Cali- 
fornia. "Talitrus pacificus (is) quite abundant 
around San Diego. Dr. Johnson used to find 
dead ones every morning at the east entrance 
to Ritter Hall. Apparently they had been at- 
tracted by the light over the entrance which 
was left on all night and killed by the insecti- 
cide there.” (Dr. T. E. Bowman, personal 
communication.) It is hardly necessary to add 
that to the Australian or New Zealand visitor 
to Southern California, the most striking bo- 
tanical feature there is the widespread cultiva- 
tion of Australian trees and shrubs. 
It has been recognised for many years that 
there is a considerable "hothouse” fauna. 
Placocephalus kewensis Mosley, a terricolous 
turbellarian found originally only in green- 
houses, and later discovered endemic in a 
different part of the world, is a good example. 
Kraepelin (I9OO) lists a considerable number 
of introduced animals of different groups 
found in hothouses in Hamburg, whilst 
Hatch (1949) discusses Isopoda, Coleoptera, 
Dermaptera, Orthoptera, and Gasteropoda 
commonly found in greenhouses of the Pa- 
cific Northwest of the United States. Hatch 
cites the isopod, Porcellio dilatatus, as a "prop- 
erly adapted species which can spread from 
greenhouse to greenhouse without being able 
to live in the surrounding situations.” In 
speaking of a "properly adapted species,” 
however, one is overlooking a rather essential 
feature of this fauna. The fact is that the 
species is properly adapted for forest floor 
conditions, but that few situations could be 
more to the liking of terrestrial amphipods 
and other cryptozoic fauna than the continu- 
ous humidity and the plentiful supply of 
leafmould for food and cover which most 
greenhouses provide. If the term "properly 
adapted” is to be used of anything in this 
context, it must be applied not to the animals 
but to the greenhouses. 
On this point, Lawrence (1953) makes a 
most interesting comparison: "The great sur- 
face evaporation of the leaves creates a humid 
mantle around the [South African rain] forest 
while the foliage of the canopy blankets the 
substratum from the direct rays of the sun so 
that it keeps its moisture longer. The atmos- 
phere . . . especially upon a hot day, often 
recalls that of a greenhouse.” 
ECOLOGY AND EVOLUTION 
The most significant recorded fact in the 
literature of the terrestrial species is the re- 
peated theme of habitat— "in damp soil in the 
forests,” "among damp fallen leaves,” "in 
burrows in soft damp soil under dead leaves,” 
"on damp earth under logs,” "under decaying 
leaves,” and so on. The terrestrial species of 
amphipods are essentially inhabitants of the 
leafmould of the forests. They have evolved a 
habit of life which, while enabling them to 
colonise a sizable area of the Indo-Pacific land 
masses, yet imposes very great limitations. 
Or, bearing in mind the direction from which 
they have colonised the forests, and that 
taken by their more advanced relatives, the 
terrestrial isopods, it would be more correct 
perhaps to say that the terrestrial amphipods 
have not yet emerged from the limitations 
imposed by their cryptozoic environment to 
any more rigorous habitat. 
The change to a terrestrial environment is 
a major one. There is a complete change of 
surrounding medium— air is substituted for 
water. There is a complete change in primary 
mode of progression, from swimming to 
jumping, and there is need for modification 
in most of the important functions of life: 
breeding, breathing, and excreting. The su- 
pralittoral species make the best of both en- 
vironments. They live within easy reach of 
the sea, burrowing in wet sand or under 
stones; they feed on seaweed and animal mat- 
ter washed up on the shore; they achieve 
distribution by means of the sea. Many spe- 
cies are able to swim to a certain extent and 
can survive immersion in sea water (Dahl, 
1946). 
