164 Christmas Island. 



2. Cardisoma carnifex (Ilerbst). 



Cancer carnifex, Herbst, Naturgesdi. dcr Krabheu unci Krebsc, vol. ii (1794), 

 p. 163, pi. xli, fig. 1. 



This species is now rcconled from tlie island for the first time, 

 the reason why it -n'as not seen by previous collectors being that 

 it occurs only in the neighbourhood of .small fresh-water streams 

 which up to the time of my visit had not been explored. In this 

 island, at any rate, this species must be regarded as a fresh-water 

 form, and, in fact, when a specimen was seen it might be taken as 

 an indication that fresh water was not far off. It lives in deep holes 

 in the mud at the sides and bottom of the brooks, and is especially 

 common near the stream about two miles north of Steep Point. 

 (See map.) 



Its colour when living is a uniform light slate- grey. This form 

 seems to differ slightly both in colour and in the proportions of its 

 carapace from specimens in the Museum Collection from Tahiti,, 

 which have been referred to the same species. 



Family OCYPODID^. 

 3. Ocypoda ceratophthalma (Pallas). 



Cancer ceratophthalma, Pallas, Spicilegia Zoologica, 1772, p. 83, pi. v, tigs. 7, 8. 



This crab is rather common on the shore platform at Flying Fish 

 Cove, where it lives under the blocks of stone, which are strewn 

 at the foot of the cliff. 



Family C(ENOBITI])..E. 



4. Birgus latro (Linn.). 

 Cancer lahv, Linu., Syst. Nat., 12tb ed., 1766, p. 1049. 



This species is found in abundance all over the island, even in 

 the densest parts of the forest on the central plateau. If in any 

 spot none are visible it is only necessary to stand still for a short 

 time before several may be seen approaching rapidly from various 

 directions. As they come near they advance more slowly and with 

 caution, the antenna; continually moving up and down alternately 

 on opposite sides. On the least alarm they scuttle backwards in 

 a succession of ungainly jerks, caused by tlie thrusts of the long- 

 front walking-legs, and as soon as possible they push the unprotected 

 hinder part of their body into any hole or crevice in tree or rock 

 that they can reach. 



In defending themselves they seem to rely chiefly on the first 

 pair of walking-legs, which arc long and terminate in sharp points ; 

 these the crab raises over its back and then strikes downward with. 



