Coloration of Marine Animals, 229 
The modification of the natural hue is thus considerable. 
Yet Hyas araneus far surpasses it in the number and variety 
of its parasitic growths, that of young specimens from cavern- 
roofs resembling the dorsum of Aphrodita. As the hue of this 
species 1s brownish purple or reddish purple, it might be 
supposed that the extraneous growths would be protective. 
Fyas coarctatus is even more subject to such growths, yet 
both, covered with parasites as they are, abound in the 
stomach of the cod, which pays scant attention to coloration. 
FHippolyte in the rock-pools of St. Andrews often differs from 
the tints of the seaweeds it frequents. Again, why should 
the female Pinnotheres in the horse-mussel be so brightly 
coloured, the male being less conspicuously so? Both are 
equally protected. Many pelagic crustaceans are also more or 
less translucent. Lysis flexuosa is grey when on sand, brown 
or green when amongst seaweed of these two colours. The 
gribble, whose sole function is to perforate wood, and thus is 
constantly sheltered, is more soberly tinted than, for instance, 
other Isopods, such as Spheroma in fissures of rocks, which 
has its under surface speckled with white, legs with brown, 
and head with brown, white, and red. Hyperta galba in the 
gastric cavities of Aurelia aurita is often reddish brown. 
Brightly coloured crustaceans like Dexamine spinosa are eaten 
by fishes. ‘The pelagic Zoee have conspicuous greenish-blue 
eyes, and the pelagic young of Crangon are brightly tinted. 
Caprella iuberculata, again, occurs in swarms on Ceramium 
rubrum, and is ofthe same tint. Jdotea pelagica on Ceramium 
rubrum is sometimes beautifully speckled with white in 
marginal scallops or central streaks, aud is thus more con- 
spicuous than usual.  Podocerus pulchellus frequents the 
same seaweed, with which it harmonizes in colour; but here, 
avain, it is sometimes gaudily tinted with reddish brown and 
white, so as to be conspicuous. Many sessile-eyed crusta- 
ceans are beautifully tinted, like Montagua monoculoides, with 
reddish-orange or orange specks in rows on the dorsum, and 
others are marbled with brown and white. The pelagic 
Eurydice pulchra and Janira maculosa of our seas are not 
inconspicuous in coloration, 
On the other hand, many land-crabs, such as Ocypoda, as 
Prof. Moseley tells us, are tinted of a bright red or other 
conspicuous hue. ‘The reddish Norway lobster frequents 
greyish mud, from which the cod picks it up so readily. 
‘The common shore-crab is often variegated with white in the 
brackish inlets of the Outer Hebrides. The reddish-orange 
Alpheus ruber is as conspicuous as it can be in the tidal pools 
ot Herm, ‘lhe multitudes of the sand-hoppers are white and 
