94 NOTE ON THE FRESHWATER CRAB, HYMENOSOMA LACUSTRLS, 



pace and appendages, and in the teeth or tuberculations 

 on the chelipeds of the male were pointed out in 1902 by 

 Fulton and Grant. The Tasmanian specimens resemble 

 those fi'om Norfolk Island in having the lateral teeth al- 

 most entirely absent, the anterior one being only faintly 

 indicated ; in Lake Takapuna specimens both teeth are 

 fairly distinct, the anterior one being prominent, though 

 bluntly rounded at the end. The Victorian specimens 

 show a somewhat intermediate condition. The male 

 specimens from Tasmania are small, and have the chelipeds 

 smooth, but this may be due to immaturitv- After 

 examining a number of specimens Fulton and Grant found 

 that the various characters mentioned were not constant, 

 and I agree with their statement that a large number of 

 adult males from each locality must be examined before 

 we are in a position to divide them into separate species 

 or sub-species. The special characters of the Tasmanian 

 specimens are, in my opinion, not sufficiently distinct to 

 warrant their separation from, the others, and they only 

 help to show how difficult it will be to find constant com- 

 binations of characters by which to distinguish the differ- 

 ent forms. Any investigation of this kind can, however, 

 be safely left for future solution : the important point at 

 present is that we have the same form of freshwater crab 

 still existing in lands now widely separated. I have drawn 

 attention to the importance of this fact in a previous 

 paper (Trans. N.Z. Inst., Vol. 47, p. 316). 



For the convenience of Tasmanian zoologists I give 

 below the chief references dealing with the subject, and also 

 the general description of the crab, which I joublished in 

 1915. 



Hymenosoma lacustris, Chilton. 



Elamena (?) lacustris, Chilton, Trans. N.Z. Inst., vol. 14, 



p. 172. 

 Tlynienosoma lacustris, Chilton, I.e., vol. 15, p. 69, pi. L 



fig. 2 a to e; vol. 47, p. 316; and P.Z.S. for 1906, 



p. 703. 

 Hymenosoma lacustris, Fulton and Grant, Proc. Roy. Soc. 



Victoria, vol. 15, p. 59, pi. 8. 

 " Carapace nearly circular, rather broader than long ; 

 " flat, naked, or with a few scattered hairs. Rostrum 

 " broad, strongly depressed, its upper surface concave from 

 " side to side, extremity in form of an obtuse angle. 

 '■ Antero-lateral margins of the carapace with 2 obscure 

 " teeth. Cheliped of male small, propod only slightly 

 " broader than the carpus, hairy. Ambulatory legs some- 



