250 



KING-CRABS. 



last nipper-like, the last or sixth ending in a number of flattened plates. The 

 basal segments of the second, third, fourth, and fifth limbs are furnished with 

 large processes, projecting into the mouth and studded with numbers of slender 

 softish spines. The mouth is thus situated between the bases of these limbs, near 

 the middle of the lower surface of the cephalothorax. The males differ from the 

 females in having the second, or second and third pairs of limbs thickened and 

 otherwise modified. In the male of the round-tailed king-crab (Limulus rotundi- 

 cauda) the second and third pairs are considerably swollen, and the two fingers 

 of the nippers cross each other when closed ; whereas in the Moluccan king-crab 

 (L. moluccanus) the immovable fingers of these limbs are reduced to short processes. 

 In distribution, king-crabs are limited to the east coast of the United States, 

 to the shores of China and Japan, and of the Indo-Pacific Islands, ranging from the 



CHINESE KING-CRAB. 



Moluccas to Singapore and Java. In the last-named area two species, L. moluccanus 

 and L. rotundicauda, occur. The Chinese species is known as L. longispinus, on 

 account of the long and strong spines projecting from the carapace and abdomen ; 

 while the North American species is L. polyphemus. The habits of the last-named 

 species are tolerably well known. It spends the greater part of the year in water 

 from two to six fathoms deep, and, being unable to swim, creeps about the bottom 

 of the sea in search of food, or even lives buried in mud, into which it scoops its 

 way. This it effects by thrusting the front edge of the carapace forwards and 

 downwards into the mud, the tail behind being used as a prop, while the legs are 

 engaged in raking up the mud and pushing it out sideways. The tail is also of 

 service in helping the animal to regain its proper position if turned upside down. 

 Digging the tip of the organ into the soil, the crab raises its body, and after a few 

 efforts succeeds in struggling over. In fact, were it not for the possession of a 

 long tail, the king-crab would be as helpless on its back as a tortoise in the same 

 position. 



King-crabs feed almost exclusively upon soft marine worms and bivalve 

 molluscs. The food is seized and tucked into the mouth by means of the legs, 



