272 DR. W. A. CUNNINGTON ON THE BRACHYUROUS [Mar. 5, 



Adult female (largest specimen) : mni. 



Length of carapace 1 3'1 



Breadth of carapace 16"9 



Fronto-ovbital Avidth 13"2 



Width offront 6-1 



Remarks. — While none of the specimens examined in 1899 

 carried ova, it is satisfactory, on compai'ison with this more ex- 

 tensive collection, to find that those i-egarded as adult were so in 

 reality. Female specimens of approximately the same size as that 

 described, but one of which is ovigerous, while the other cai-ries 

 the already liberated young, occur in the recent collection. 

 Indeed we have further a female with total breadth of only 

 12-4 mm., but which is nevertheless ovigerous. The average 

 size of the eggs themselves, which are not quite round, is 

 1-9 X 1 "5 mm. 



The much smaller size of this species enables it to be distin- 

 guished at once from adult specimens of P. armata, but, apai't 

 from that, the great relative breadth of the front and size of the 

 orbits are differences easily recognised. Among the number of 

 specimens which we now possess there exists considerable indi- 

 vidual variation in respect to the development of certain spines, 

 and this accounts for a slight discrepancy which may be noticed 

 between the foi-egoing description and that given in the first 

 instance. In the original type specimens, the spine on the carpus 

 of the cheliped, above the articulation with the hand, is indicated 

 but slightly, if at all. As it is, however, very well developed in a 

 number of individuals, it is now included among the specific 

 characters. Again, certain of the new specimens exhibit a small 

 spine at each extremity of the front, and have a slight indication 

 of sub-orbital spines, while others show no trace of these features. 

 A more complete description of the fingers of the chelipeds is 

 now given, and from my own observations I can add the colora- 

 tion during life. 



Occurrence. — The type specimens described in 1899 were 

 obtained, according to the information supplied me by Mr. Moore, 

 from Kituta Bay (south end), while he had also taken specimens 

 at Niamkolo (south end) and Sumbu on the west coast. The 

 Crabs were said to have been captured in fairly deep water — never 

 less than 60, and from that to 500 feet deep. In his book on 

 Tanganyika, however, Moore states* that the specimens were 

 obtained in water varying in depth from 500 to 600 feet. He 

 also adds that the Crab occurs throughout the lake. With the 

 latter statement, the experience of the recent Expedition is quite 

 in accord ; but whether the original individuals came from such 

 very deep water or not, it is cei-tainly a fact that the species ma}' 

 be found in much shallower regions. 



Niamkolo Bay (south end): a large number of specimens 



* Op. cit. p. 280. 



