258 DK. W. A. CUNNINGTON ON THE BRACHYUROUS [Mar. 5, 



4. Zoological Results of the Third Tanganjdka Expedition, 

 conducted by Dr. W. A. Cunnington, 1904-1905.— 

 Report on the Brachyurous Crustacea. By William 

 A. CuNNiNGTON, B.A., Ph.D., F.Z.S. 



[Received Marcli 5, 1907.] 

 (Plates XYI. & XVII.* and Text-figure 84.) 



1 . Introduction. 



Since the year 1896, when Mr. J. E. S. Moore paid his first 

 visit to Lake Tanganyika, our knowledge of the fauna of that 

 lake, and of the interesting problems which are connected with it t, 

 has considerably advanced. The single representative of the 

 Brachyura then collected was described somewhat later %, but 

 already, in 1887, a description had been given by Milne-Edwards § 

 of another form brought from the lake by Captain Joubert. The 

 description of this last-mentioned type was unfortunately very 

 incomplete, while at that time no male specimen had been 

 obtained. During Mr. Moore's second expedition, in 1899-1900, 

 he succeeded in collecting further examples of both the species 

 already known, and furnished male specimens of the form which 

 Milne-Edwards had described from the female alone. Finally, a 

 Third Tanganyika Expedition was dispatched in 1904, with the 

 conduct of wdiich I had the honour of being entrusted, and which 

 has added yet again to our knowledge of the Brachyurous 

 Crustacea of the lake. 



The very earliest facts which were learned respecting the fauna 

 of Tanganyika seemed to show that the animals it contained 

 were not merely of an unusual type, but were different from those 

 living in the other big African lakes. It is an interesting fact 

 that, with the lapse of time and a very great increase in our 

 knowledge of the lakes of Central Africa, this dissimilarity of 

 Tanganyika has been not only confirmed, but rendered more and 

 more striking. Among other animal groups, that of the Brachyura 

 afibrds an excellent example of this remarkable state of things ; 

 so that a double purpose will be served by the description in this 

 paper of Crabs from Nyasa, which lake has the normal charac- 

 teristics of the African fresh- waters. 



The collection of Crabs made during this Expedition contains 

 representatives of five species, of which two alone have been 

 previouslj'^ described. By the kindness of Dr. W. T. Caiman, I 

 have been permitted to examine and compare with the collection 

 a large number of specimens of nearly allied forms, belonging to 



* For explanation of the Plates, see p. 276. 



t Moore, ' The Tanganyilca Problem ' (London, 1903). 



J Cnnnino-ton, Proc. Zool. Soc. 1899, p. 697. 



§ Ann. Sci. Nat. 7" ser., Zool. t. iv. (1887) p. 146. 



