] 2 



To review the species of Hymenicus is very difficult to any one, who has no opportunity 

 of examining the type specimens or a rich material from New Zealandian shores. 

 Considering the shape of the rostrum, two groups are to be distinguished : 

 I. Front triangular or slightly truncate : 

 H. lacustris (Chilton) 

 H. haasti Filhol 

 H. edwardsi Filhol 

 H. pubescens Dana 

 H. australis Haswell. 

 II. Front trilobate : 



H. varius Dana 



H. novae-zealandiae Dana 



H. cooki Filhol 



H. marmoratus Chilton. 



i . Hymenicus lacustris (Chilton). 



1882. Elamena (?) lacustris Chilton. Transact. Proc. N. Z. Inst., v. 14, p. 172. 



1883. Hymenosoma lacustre Chilton. Transact. Proc. N. Z. Inst, v. 15, p. 69. 



1902. Hymenosoma lacustris Fulton et Grant. Proc. R. Soc. Victoria, N. S. v. 15, p. 59, pi. 8. 



This species is remarkable above all others by its inhabiting fresh waters. Judging from 

 the figures of Fulton and Grant I think the species is to be placed in Hymenicus and not 

 in Hymenosoma. 



The lateral teeth of the carapace are absent in specimens from Norfolk Island; in those 

 from Victoria the posterior teeth are wanting, and in specimens from New Zealand (Lake 

 Pupuke, Auckland) the two pairs are both present, though obsolescent. The rounded, triangular 

 rostrum, the bifid, prominent inner angle of the wrist, the finely-crenulate proximal part of the 

 lower border of the palm, and the elongately-triangular abdomen of the d" seem to be the 

 principal features of the species, but there are slight variations in specimens from different 

 localities 1 ). 



2. Hymenicus ptiöescens Dana. 



1851. Hymenicus pubescens Dana. Journ. Ac. Nat. Sc. Philadelphia, 185 1, p. 254. 



1852. Hymenicus pubescens Dana. U.S. Expl. Exp., Crust, p. 388, pi. 24, f. II. 



1853. Elamene quoyiï H. Milne-Edwards. Ann. Sc. Nat., (3) t. 20, p. 223, pi. n, f. 3. 

 1865. Hymenicus pubescens Heller. Reise "Novara", Crust., p. 6j. 



1885. Elamena quoyiï Filhol. Miss. 'ile Campbell, t. 3, prt 2, p. 403. 



This species is very little known. I have united Elamena quoyi H. Milne-Edwards with 

 it, though with a query; in comparing Dana's figure with that of Milne-Edwards the general 

 appearance, and especially the shape of the rostrum, is unmistakebly the same; only the legs 



1) In Mem. Austral. Mus., n° 2, 1889, p. 34 Whitelegge mentions a fresh-water species of Hymenicus found at Lord Howe 

 Island. Though nothing more is known about this form it is likely to be referred to the present species. 



