LIMULI. GEOGRAPHICAL DISTRIBUTION OP CRUSTACEA. 281 



the central line. The Limuli are con fined to the shores of 

 tropical Asia, the Asiatic Archipelago, and tropical America. 

 As the best-known species comes from the Mollucca Islands, they 

 are sometimes termed Molucca Crabs. Of their habits very 

 little has been ascertained. They appear to prefer the neigh- 

 bourhood of sandy shores, and it is said that when kept from 

 the water, they bury themselves in the sand, in order to avoid 

 the violent heat of the sun, which causes them speedily to perish. 

 They feed upon animal flesh. The long horny process of the pos- 

 terior shield is not developed in the young animal ; which also 

 wants the posterior or branchial members. This process is used 

 by some of the Malays as a point for their arrows ; the wounds it 

 makes being dangerous, like those made by the spines of many 

 Fishes, on account of their jagged character. On the coast of 

 America, where the Limulus is known as the Casserole Fish, 

 the shell is employed as a ladle for water. Fossil remains of 

 this genus are not uncommon in the Secondary and Tertiary 

 strata ; and it may be further remarked that, in several particu- 

 lars, the Trilolites may be regarded as having been probably 

 analogous to it. 



Geographical Distribution of Crustacea. 



The extensive study of this large and important class, by 

 M. Milne-Edwards, has enabled him to arrive at some very 

 interesting conclusions in regard to its Geographical Distribution. 

 An outline of these will be here introduced, because they would 

 probably serve, with some modifications, to represent the general 

 facts relating to the distribution of other Classes. 



818. It has been pointed out, in the preceding sketch of 

 the principal forms of the Crustacea, that different species have 

 different localities, or residences assigned to them (as it were), 

 on the surface of the globe. We have seen that some are exclu- 

 sively confined to fresh water, that others are inhabitants of the 

 brackish water of estuaries, that others take up their abode on 

 the shore, where they are periodically covered and left dry by 

 the tide, that others frequent the shallow waters in the neigh- 

 bourhood of the shore, that others are found near the bottom 

 of the deeper waters, at no great distance from land, that others, 



