1909.] CRUSTACEA FROM CHRISTMAS ISLAND. 709 



The merus of the walking legs has two or three strong teeth at 

 the distal end of its hinder edge and, in addition, the merus of the 

 last pair has two smaller teeth side by side near the proximal end. 

 The legs cai-ry rather long hairs and the dactylus is strongly 

 spined. 



Measurements : — 



Male. Female (ovigerous). 



Length of carapace 4*5 mm. 3"75 mm. 



Breadth of „ 6-6 „ 5-75 „ 



(between orbital angles) 



Breadth of front 3-75,, 3-0 „ 



Remarks : — Assuming that the fine beaded lines on the upper 

 surface of the hand represent the "pectinated ridges" found in 

 the males of some other species of Sesarma, this little species will 

 fall into the third section or sub-genus (Parasesarma) in de Man's 

 classification of the genus. Within this section it comes into 

 relation with a group of species, all of small size, which are 

 distinguished by the toothed meropodites of the walking legs. So 

 far as I am aware only four species of this group have been 

 described — S. vestifa Stimpson*, S. andersoni de Man, S'. eda- 

 mensis de Man, and *S'. hatavica Moreira (= ^S'. harhimana de 

 Man, nee Cano). In all of these the pectinated ridges on the 

 upper surface of the hand are more strongly developed than in the 

 new species and are difierently arranged ; the upper edge of the 

 dactylus of the chelipeds is strongly "milled" in all except 

 >S'. vestita, where it is stated to be acute ; and none of the species 

 possesses teeth at the proximal end of the merus of the last pair 

 of legs. Further, >S'. hatavica is distinguished by the tufts of 

 hair on the fingers, 8. edamensis by the much broader legs, 

 *S'. andersoni by having the carapace smooth and the sides much 

 less strongly convergent posteriorly, and S. vestita by having the 

 carapace only a little longer than broad (breadth-ratio 1*03 as 

 against 1-46 to 1-53 in the new species). Outside of de Man's 

 third section, the only species of Sesarma which are described as 

 having the meropodites of the legs toothed are 8. minuta de Man 

 and S. harhimana Cano, both of which are separated from the 

 species here desci-ibed by the presence on the lateral margin of a 

 tooth behind the orbital angle. 



The specimens of this crab were collected on the shore at 

 Flying-fish Cove. 



The specific name is chosen in compliment to Sir John Murray, 

 K.C.B., F.R.S., by whom the specimens described in this paper 

 have been presented to the British Museum. 



* This is referred bj' de Man to liis first section (Zool. Jalirb. ii. p. 644, 1887), but 

 tlie recently published description and figure (Stimpson's Rep. Crust. N. Pacific 

 Espl. Exp.,'Smitlisonian Miscell. Coll. xlix. p. 136, pi. xiii. fig. 6, 1907) show that 

 the species possesses pectinated ridges on the upper surface of the hand and must be 

 referred to de Man's third section. 



