Table-case 
No. 6. 
44 
Guide to Crustacea. 
Fig. 25. 
Arcturus baffini , female, carrying a cluster of young ones on its antennae. 
[Table-case No. 6.] 
terrestrial species and their marine relatives. Porcellio scaber 
(Fig. 26) is one of the very common garden species. 
The Isopods belonging to the Sub-order Epicaridea are all 
parasitic on other Crustacea, and their structure presents, in the 
adult state, a great variety of modifica- 
tions. The two sexes are often very dis- 
similar in size and shape, and some 
species are hermaphrodite. A specimen 
of the common Prawn ( Leander serratus ) 
is exhibited which has, on one side of 
the 
sence in the gill-chamber of the parasite 
Bopyrus squillarum. The female of the 
parasite, taken out of the gill-chamber, is 
shown alongside. The male, in this 
species, is almost microscopic in size, and 
is commonly found clinging to the under 
side of the female. 
A still more remarkable form is shown 
in the drawings of Portunion maenadis, 
a parasite of the common Shore-crab, 
Carcinus mamas. The figure on the right 
carapace, a swelling due to the pre- 
Porcellio scaber, female, 
dorsal view, enlarged. 
(From Lankester’s 
“ Treatise on Zoology,” 
after Sars.) 
