72 INVERTEBRATE ANIMALS. 



Group 176.— ANOMOURA SUPERIORA. Dana. Several 

 species of Dromia carry on the carapace a sponge-like 

 mass of sufficient size to conceal the whole animal. 

 M. Edwards remarks, that the Dromia fixes the load on 

 its back by the aid of its posterior pair of legs. Some 

 other crabs have similar habits, in consequence of which 

 the older individuals resemble walking gardens of vari- 

 ous kinds of Zoophytes. Mr. T. Higgin observed in the 

 young of Hyas coarctatus that its bristles were sharply 

 recurved at the point, forming a forest of hooks capable 

 of entangling loose sprays of Zoophytes and Sponges, 

 some of which would take root and at length form a 

 thicket, under cover of which the robber crab might 

 readily make a prey of unwary intruders. 

 Estimated number of species : recent, 12 ; British, 1. 

 H Examples of Dromia, Dynomene, Homola, 

 Ranina, &c. 



Tribe BRACHYURA. ^po^x^c, short ; ohpu, a tail. 



This tribe includes all the most highly organised 

 Crustaceans. The nervous system is much more concen- 

 trated forwards than in the inferior tribes. The abdomen 

 is slightly developed, and is not used to assist the 

 animal in swimming. The larval form, Zoea, long 

 considered to be a distinct animal, bears some resem- 

 blance to the adult type in the Macroura. 



Section A. — Crabs ivith mouths much narrowed in front = 

 Famille des Oxystomes (Milne Edwards). 



Group 177.— Families LEUCOSID^, CORYSTID^, and 

 DORIPPIDiE. 



Many of the Leucosidce are readily distinguished by 

 their convex form narrowed in front into a kind of 



