126 A NATURALIST ON DESERT ISLANDS. 



access to the shell and leads to the further development 

 of the eggs until they are hatched. Whether the 

 hatched larvae undergo a part of their development 

 in the shell of the mother, which is thus filled with salt 

 water, is a moot point, but Mr. Borradaile (loc. cit.) has 

 himself seen in Ceylon two species of hermit-crabs of the 

 same genus as the West Indian, covered with hatching 

 embryos (Zocea) ; and doubtless these quickly get washed 

 off by the waves, as they break upon the beach, and then 

 flow onwards over the bodies of the adult crabs. Thus 

 are the young launched upon their temporary free swim- 

 ming marine existence, where they pass from a sosea 

 stage, to a metazosea, and finally into a creature called a 

 glaucothoe.* When they return, they appear as small 

 adult land hermit-crabs, each having appropriated a 

 small shell suitable to its size. 



To complete this long life history, for the length of which 

 we must earnestly apologise, although it seems so inter- 

 esting, not only from the actual strange facts which it 

 discloses, but from the far larger problems of evolution 

 which it implies ; we may briefly state that the hermit-crab, 

 as regards its food, is omnivorous, and is, in fact, a most 

 useful scavenger of tropical islands and foreshores. On 

 occasions they are cannibals, but they do not seem to 

 fight among themselves so much as the hermit-crabs of 

 the sea. The sense of smell which has been developed 

 in these hermit-crabs seems to be something quite remark- 

 able, and analagous to that of vultures (if indeed, vultures 

 do possess an acute sense of smell) ; for if by any chance 

 the body of a fish or animal is washed up by the sea upon 

 the shores of a tropical island, hermit-crabs will descend 

 in their thousands, from far and wide, to the scene of 

 putrefaction ; and marching along in great armies will 

 quickly foregather to the feast ; a sight which has been 

 actually described by Mr. Wood- Jones in his "Corals 

 and Atolls." 



* Metamorphosis of the Hermit Crabs by M. T. Thompson, Proc. 

 Boston Soc. Nat. Hist,, xxxi,, 1904, p. 147, 



