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[VOL. II 
D. warwickii and D. grayii, all of which live for a considerable time after their host 
has been removed from the water. There is no evidence that even the internal 
species are detrimental to any appreciable extent to the crustacean in whose gill- 
chamber they live. Possibly they may even be to some slight extent beneficial in 
aiding respiration by the movements of their cirri and by eliminating organisms 
which, if not actually the producers of disease, would be out of place in the breathing 
apparatus of any animal; for their alimentary canal is usually crammed with diatoms, 
foraminifera and other protophyta and protozoa. The weight of the large numbers 
of external barnacles, mostly belonging to this genus, which some comparatively 
small decapods have to bear must be a strain upon them, and pelagic species such as 
those of Neptunus must be somewhat hampered in swimming by the tassel-like 
masses of D. warwickii adhering to their swimming legs and to the sides of their 
carapace. I have seen more than 600 specimens of D. grayii attached to a single 
snake, and the number of individuals of D. warwickii attached to a single crab is 
often almost as great. It is probable, however, that soon after the barnacles have 
attained such numbers the crab or lobster or snake casts it skin, for when such 
masses are present they obviously include barnacles of several generations and only 
a few are of full size. In the case of bottom-haunting crabs, moreover, it is by no 
means improbable that the barnacles aid them in concealing themselves. In the 
Colombo Museum there is a specimen of Dorippe dorsipes in which the whole of the 
posterior part of the carapace and the base of the posterior limbs are concealed by 
the masses of D. warwickii which cluster upon them. It is well known that the 
crabs of this genus frequently bear upon their back, by means of limbs apparently 
modified for the purpose, a gastropod operculum or some similar object to which an 
actinian is attached. In the case of the Colombo specimen the barnacles completely 
take the place of this peculiar buckler, and the crab would have probably found it 
impossible to hold any thin object in the usual position, had there been any necessity 
for it to do so. 
For these reasons it is impossible to class the species of Dichelaspis as actual 
parasites. 
