on a Crab from Christmas Lslund. 



540 



the liand, where it hears a siogle polyp. On the walkins;- 

 k'gs the main trunk of the hydrorhiza, on reaching the joint 

 hetween the raerus and carpus, divides into two brandies 

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

 extent of niovonient is least, and reunite to run along tlio 

 iijipcr e<\(xe of the carpus and propodus. On each leg, at the 

 ])oint of reunion of tlie branches, near the proxin)al end of 

 the carpus, a l>olyi) 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 unsymnietrically 

 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 leer on the left side. 



Ficr. 1. 



Fig. 1. — Xanthi'as hastcelli CSUers) from Christmas Island, carrying- aa 



epizoic hydroid {Sti/htctis (? ) sp.). X 5. 

 Fig. 2. — Sfylacti.i (?) 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 

 hasicelli show the remains of similar hydroid colonies. Tiie 

 hvdrorhiza outlines the areas of tlie cara|)ace much as in tlie 

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

 remark, " the sutures defining the various regions of the 

 dorsal surface very distinct." The polyps are very badly 

 preserved, having apparently suffered drying, and it is not 

 possible to state whether they agree in structure with tliose 



