on a Crab from Christmas Island, 



549 



the hand, where it bears a single polyp. On the walking-- 

 legs the main trunk of the hydrorhiza, on reaching the joinb 

 between the raerus and carpus, divides into two branches 

 which cross the joint at the condyle on each side, where the 

 extent of movement is least, and reunite to run along the 

 upper edge of the carpus and propodus. On each leg, at the 

 point of reunion of the branches, near the proximal end of 

 the carpus, a polyp is attached. 



All the polyps mentioned, namely, two on the carpus and 

 one on the propodus of the cheliped and one on the carpus of 

 each walking-leg, are symmetrically developed on both sides 

 of the crab. Only two small polyps are unsymmetrically 

 situated, one on the upper edge of the merus of the right 

 cheliped and one at the distal end of the merus of the pen- 

 ultimate leg on the left side. 



Fia-. 1. 



Fig. 1. — Xanthias hasivelli {'M\qx&) from Christmas Island, carrjing- au 



epizoic hydroid {Stylactis (?) sp.). X 5. 

 Fig. 2. — Styladis (?) sp., one of the polyps further enlarged. The form 



of the hypostome is indicated by a dotted line. 



As already mentioned, the three type specimens of Xanthias 

 hasivelli show the remains of similar hydroid colonies. The 

 hydrorhiza outlines the areas of the carapace much as in the 

 Christmas Island specimen, and no doubt accounts for Miers's 

 remark, " the sutures defining the various regions of the 

 dorsal surface very distinct." Tlie polyps are very badly 

 preserved, having apparently suffered drying, and it is not 

 possible to state whetlier they agree in structure with those 



