310 THE OCEAN WORLD. 
rocks and other marine bodies, and generally ata fixed depth. <Ascidia 
microcosmus, a. Mediterranean species, represented in Fig. 123, may 
be given as an example of this division of Tunicates. The name of 
microcosmus, or the little world, is probably given to the species from 
its being inhabited by quite 
an animated colony of alge 
and corals, which dwell 
upon its surface, and give 
it a very peculiar, but not 
very attractive, appearance. 
The flavour of these mollus- 
coids is very strong, which 
does not, however, hinder 
the poorer dwellers on the 
sea-shore from eating them. 
Phaillusia is another genus 
of the group.  Phallusia 
grossularia is of a reddish 
colour, and about the size 
of a currant-berry: it usually 
lodges itself in the oysters 
of certain localities. At 
Ostend another species, 
Phallusia ampulloides, is 
found in prodigious quan- 
tities in the oyster parks, 
and is parasitic on living 
lobsters. 
Social Tunicates em- 
brace such forms as are 
connected together by a 
common stoloniferous pro- 
=== longation, but remain free 
~ “and unconnected in all 
other respects.  Ascidia 
pedunculata (Fig. 124) may 
be given as an example. 
The Composite Tunicates are still more intimately associated 
together; a great number of these little beings living together in a 
single mass. Such are the many species of such genera as Botryillus 
and Pyrosoma. 
Botryllus is a genus perhaps the most interesting of all those under 
Fig. 124.—Ascidia pedunculata (Milne-Edwards). 
