KING-CRABS 



369 



(p. 225), and the Mantis Shrimp [Sqtdlla mantis) tunnels in 

 banks covered with marine vegetation (Zostera). This creature 

 is of special interest in the present connection, because it lays 

 its eggs in these burrows, instead of carrying them about. The 

 attenuated larva is known as an Alima (fig. 891). 



Among Crustaceans of the Sand-Hopper kind (Amphipoda) 

 the Caddis Shrimps {CorophiidcB) construct tubular or ovoid nests 

 from fragments of sea-weed or other materials. The bodies of 

 these creatures are cylindrical, in correspondence with the shape 

 of their dwellings, and not flattened from side to side as in 

 ordinary Sand- Hoppers. 



LIFE-HISTORY, &c., OF KING-CRABS 

 (Xiphosura) 



The King-Crab or Horse-shoe Crab {Liinulus), which is 

 the only living representative of this ancient group, lives in 



Fig. 892. — Trilobite Larva of King-Crab [Limulus polyphevuts)^ enlarged 

 A, Upper side. B, Under side. 



shallow water, and comes as near the coast as possible during 

 spring-tides for spawning purposes. The female digs a hole for 

 the reception of her eggs, which are afterwards covered over 

 with mud by the movement of the water. One reason for 

 choosing a spot near land for this purpose appears to be that 

 incubation may be hastened by the warmth of the sun, at the 

 times when the sea goes down. The eggs hatch out into little 

 Trilobite larvae (fig. 892), so called because they have a certain 

 resemblance to the extinct animals of that name. 



