MARINE BIOLOGICAL STATION AT PORT ERIN. vi 
loscombu, Capulus hungaricus, Scaphander lignarius, 
Otina otis, Bulla hydatis, and Melampus bidentatus, 
mostly from Bay Fine. 
Molgula citrina and Ascidia depressa are under stones 
near Port St. Mary, and many species of compound 
Ascidians, especially Botryllids, such as Botryllus morio, 
B. aurolineatus, B., violaceus, and Botrylloides albicans, 
are common both at Port Erin and Port St. Mary. 
PROTECTIVE COLOURING. 
The common shore prawn, Virbius varians, found at Port 
Erin, and probably all round the coast, is a most marked 
case of protective colourmg. Specimens taken from a 
“‘zostera prairie’ are of the same bright green colour as 
the “‘Sea grass,’ to the blades of which they adhere 
closely, (see Pl. VI. fig. 3). Their eggs also are green. 
Specimens, however, which are found amongst the red 
sea-weeds, such as half rotten masses of Delesseria and 
Rhodymenia (see fig. 2), are either completely red, or red 
with a slight mottling of white or grey. Specimens found 
on a sandy bottom, or on small gravel, are mottled black, 
erey and white. These are all cases of simple, but very 
complete, protective colouration. 
The specimens of Virbius, however, which occur upon 
the dark brown sea-weed Halidrys siliquosa present a more 
complicated case, as they actually mimic the chambered 
capsules of the Alga, both in form and colour, and also 
in position. The Crustacean is here of a dark brown 
colour, and has the habit of clinging to the stem in such 
a position that the body extends straight outwards in a 
stiff attitude (see Pl. VI. fig. 1); and the plant may be 
shaken to some extent without affecting the pose of the 
Crustacean, and its resemblance to the capsules. 
These are clear cases of the Crustaceans having become 
