LOBSTERS, CRAYFISH, ETC. 



'■65 



terrestrial forms is the great cocoa-nut crab (Birgus latro), found in the islands of 

 the Indo- Pacific seas, and remarkable not only for its great size and habits, but also 

 for having the abdomen symmetrical and covered above with a series of horny plates. 

 These animals inhabit deep burrows, which they hollow out beneath the roots of 



trees, and carpet with fibres stripped ,„_ 



from cocoa-nuts. Periodically, how- 

 ever, they are compelled to visit the 

 sea to moisten their gills ; and here 

 they lay their eggs, the young being 

 hatched and living for some time on 

 the coast. They live principally 

 upon cocoa-nuts, which fall from the 

 palms, but they do not climb the trees 

 after the fruit. To get at the con- 

 tents of the nut, the crab first tears 

 away the fibre overlying the three 

 " eyes," and then hammers away 

 with its claws at the latter until a 

 hole is made, when it extracts the 

 kernel by means of its smaller 

 pincers. Some observers state that 

 after drilling through the perforated 

 eye, the crab grasps the nut in its 

 claws and breaks it against a stone. 



In the next tribe, or Thalas- 

 sinidea, the carapace is much com- 

 pressed and has a small rostrum, but 

 the abdomen is well developed and 

 often wider in the middle than in 

 front. As in the short-tailed group, 

 the fourth pair of thoracic limbs are 

 enlarged and generally completely 

 chelate, while the four succeeding 

 pairs, of which the last is smaller 

 than the rest, usually terminate in 

 simple claws. All the members of 

 this group are exclusively marine, 

 living at the bottom of the sea 

 buried a foot or more in the mud. 

 The accompanying figure represents 

 a species (Thaumastocheles zeleuca) 

 obtained at a depth, of four hundred fathoms in the West Indus. It is character- 

 ised by the extraordinary development of the pincers of the right claw, which are 

 not only very long and slender but beset with spine-like teeth. The creature is 

 totally blind, having lost both eyes and eye-stalks. 



In the tribe of the Scyllaridea none of the limbs of the thorax are truly chelate, 



ONE-CLAWED LOBSTEB, Thau mastocheles zeleuca (nat. si; 



