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“was fully grown and had exerted sufficient pressure upon the left 
gill-cover of the host to cause it to become conspicuously deformed. 
Of greater importance for the determination of the species is the 
character of the pleopods, which are flat, leaf-like and perfectly 
smooth (Pl. I., Fig. 4) in contrast to those figured by Bonnier for 
P. galatheae, which are markedly tuberculate and appear to be 
cylindrical rather than lamellar (Pl. I., Fig. 5) The first pair 
of ineubatory plates differ from those of Bonnier’s specimen in 
certain points of detail, the importance of which, however, it is 
not intended to stress. 
British records of Plewrocrypta galatheae on Galaihea squamifera 
include those of Loughrin from Polperro, of the Rev. A. M. Norman 
from the Shetlands and of Tattersall from the west coast of Ireland. 
The form figured by Bate and Westwood as Phryxus longibran- 
chiatus from G. squamifera, which Sars has described as a distinct 
species Pleurocrypta longibranchiata, is regarded by Bonnier as 
merely the young form of P. galatheae. Bate and Westwood also 
refer to the Rev. Norman’s announcement of this same form Phryxus 
longibranchiatus as occurring upona specimen of Pagurus thompsonr 
dredged from Tynemouth, 1863, but this is almost certainly an 
error—as Norman himself later admitted—due to confusion of 
this form with a species of Pseudione, probably P. hyndmanni. 
Dr. W. T. Calman has very kindly compared my specimen with 
those of P. galatheae in the Norman collection, labelled as from 
Starcross (Devon), from Jersey and merely as ** British,” and states 
they all differ from my own in general appearance and in having 
the pleopods conspicuously more tuberculated. 
There is room for confusion in connection with the identification 
of Epicarid parasites as a result of the difference of opinion among 
specialists as to whether a particular species is or is not definitely 
restricted to a single species of host. Giard and Bonnier take the 
first view, Sars and Hansen the second. Thus, as already noted, 
Sars ascribes to Galathea squamifera a second species of parasite P. 
longibranchiata, in addition to the one (P.galatheae) already admitted, 
Tattersall, who has taken both forms from separate individuals of G. 
squamifera, inclines to agree with Giard and Bonnier that they 
are really one and the same species. The fact that Sars’ P. long- 
branchiata is distinctly smaller than P. galatheae also points to 
its being a young form of the latter. In any case, the authority 
