240 



L. A. BORllADAILE. 



very great diversity, will be found, I believe, to be connected with the nature of the ground 

 on which the animal's life is passed, whether it live among stones or in sandy places or in 

 coral stocks, and to its habits, whether it crouch with folded limbs under shelter or hold 

 fast with its legs. 



Fig. 42. Ends of the walking legs of Xanthid Crabs. A. Tip of tbe end-joint in Cnrpilius convexus (Fig. 41 A). 

 B. Same part in Trapezia ferruginea (Fig. 41 F). C. Whole end-joint in Actaea speciosa. The drawings are 

 not made to scale, .-1 being much less enlarged than iS or C. 



A number of examples of this feature may be found in the illustrations scattered through 

 the present paper, but in the accompanying figure (Fig. 42) three of the most unlike of 

 them are shown enlarged. Carpilius convexus is a heavy-bodied, spindle-shanked crab, too 

 big and clumsy to climb among the branches of coral stocks, which leads a sluggish and 

 uneventful life among objects on the bottom, and has even been found enclosed as in a 

 cage by the growth of coraP. Its legs {A) accordingly end in a very simple claw. Trnpezia 

 ferruginea is a typical crab of the living coral, and we may suppose that the remarkable 

 ending of its legs (B) is in some way connected with this fact. But what can be the 

 meaning of the curious brush of hairs at the end of the first walking leg of Actaea 

 speciosa (C), and why this structure is not found on the other legs, cannot as yet be even 

 guessed. Some remarks on the different ways in which the last joint may be hinged on 

 to that before it will be found below on p. 242. 



According to Henderson [Tr. Linn. Soc. Zuol. (2) V. p. 332] the colour markings of shore 

 Decapoda are generally protective in their nature, but this is certainly not always the case, 

 as, f)r instance, in Trapezia and Carpilodes. 



In another respect, besides those of structure and habits, the Xanthids offer a contrast 

 to the swimming crabs, described in the last number of this publication, which, next to 

 them, are the most conspicuous family of crabs in the Tropics. They are, with some striking 

 exceptions, not very variable, and are not varietal, save in a few cases. In the Trapeziinae, 

 however, varieties appear, and the genus Piliimnus shows a remarkable plasticit}' of constitu- 

 tion, which leads to the formation of numerous local species and will be alluded to again 

 below ^ 



1 Coutiere, Bull. Mas. hist, iiat., 1898, 5, p. 238. 



- P- 



244. 



