20 ANIMAL PARASITES AND MESSMATES. 



without doubt the same animal that Mons. Peters, of 

 Berlin, found on the coast of Mozambique, and of which 

 we have spoken before. 



A little crab is known to live near the coast of Peru 

 {Fahia Chilensis, Dana), which exists under somewhat 

 different conditions. He chooses, not a bivalve mollusc, 

 but a sea-urchin (Euriechinus imhecillus, Verrill), and 

 lodges in the intestine, near its termination, so as to 

 seize as they pass by all those living creatures which are 

 attracted by the odour. Doubtless, the delicacy of our 

 sense of smell is disgusted by such a mode of seeking 

 food ; but this predilection may have a reason with which 

 we are not acquainted. There are a considerable number 

 of other species which live under similar conditions. 



On the coast of Brazil, my son found two couples of 

 crabs in the tube of a very long annelid, narrow at the 

 ends, and wide in the middle. The tube was too small 

 at the end to allow them to escape. These crustaceans 

 had, no doubt, penetrated thither before they had at- 

 tained their full size. 



A crab of the family of the Maidae conceals itself in 

 the substance of a polypidom very common in the Yiti 

 Islands, in company with a gasteropod mollusc, and 

 both of them assume the exact colour of the polypidom. 

 This is a new kind of mimicry. This crab is known by 

 the name of Pisa Styx, the gasteropod is a Cyprsea, the 

 polyp is the Melithea ochracea. A decapod crustacean, 

 the Galathea spinirostriSy seeks for a Comatula, the 

 colour of which it exactly imitates, and with which it 

 lives on the most friendly terms. 



The holothurise, of which we have already spoken, 

 appear to afford an abode to many animals : indepen- 



