BRITISH STALK-EYED CRUSTACEA. 259 



in fact many are found living together under similar conditions. In 

 describing the species of this class we shall refer more fully to this 

 striking characteristic. 



Anomoura. 

 Dromia vulgaris, Edwards. 

 This common Mediterranean species has the carapace, when 

 the limbs are at rest, almost round like a ball. The whole body, 

 excepting the forceps, is densely covered with a warm brown 

 mass of closely-set setas ; this gives it the appearance of an 

 Echinoderm (Amphidotus cordatus), for which at a short distance 

 it might easily be mistaken. Its first pair of legs are massive ; 

 the extreme tips of the forceps are bare and shining, and are of 

 a most exquisite pink colour. The remaining legs are com- 

 paratively short and armed with strong hooked claws, the last 

 pair being rudimentary and curiously turned upwards, so as to 

 rest flat upon the upper surface of the carapace. This un- 

 natural position for ambulatory appendages may be accounted for 

 by two remarkable specimens obtained from the Channel, off the 

 Sussex coast, now in Mr. Carrington's collection. These two 

 animals bore on each of their backs a finely grown sponge, each 

 large enough to protect its host from observation. Unlike the 

 instances to which we have already referred, notably that of 

 Pisa Gibbsii, where the sponge grows in the villous coat of the 

 carapace, this is not so with Dromia ; for although the lower 

 surface of the sponge was a perfect mould of the carapace of the 

 crab, it was nevertheless quite free, and simply held in its place 

 by the sharp claws on the two pseudo-legs already described as 

 turned over on to the carapace of the animal. This instance of 

 protective adaptation is without exception the most wonderful 

 that we have yet met with in the whole of the British Crustacea. 

 Although there are many very striking cases constantly attracting 

 attention, they may be said almost to exist in spite of the animal 

 itself; here, however, we have an example of quite another kind. 

 It appears that the animal has actually taken, in its small 

 rudimentary feet, a sponge which it has held upon its carapace, 

 but not permitted it to obtain a hold upon that structure. At 

 the same time the sponge has been able to grow ; the remarkable 

 way in which it has taken the form of the carapace of the animal 

 without adhering to it is a proof of this. 



The abdominal segments of Dromia vulgaris are somewhat 



