6 Annals of the South African Museum. 



1902. Halimus diacanthus, M. J. Eathbun, U.S. Nat. Mus., 



vol. xxvi., p. 29. 



1903. Hyastenus diacanthus, Nobili, Boll. Mus. Zool. Torino, 



vol. xviii., N. 455, p. 27. 



The synonymy of the species down to 1895 is supplied in the 

 reference to Alcock, the transference to Hyastenus commencing 

 with A. Milne-Edwards in 1872. The distribution of the uncinate 

 setae is discussed by C. W. S. Aurivillius in his treatise on the 

 masking habits of the Oxyrrhyncha, p. 51, pi. 2, fig. 5, 1889. Among 

 the numerous Indian species Alcock distinguishes the present one 

 as belonging to a group in which the carapace when denuded is 

 smooth and polished, with a few large spines ; in common with 

 H. spinosus, A. Milne-Edwards, it has the " carapace triangular, 

 with a large epibranchial spine and at least one large subhepatic 

 tubercle on either side," and is distinguished from the species men- 

 tioned by having a single acuminate tubercle in the middle line on 

 the gastric region, and none on the intestinal, whereas H. spinosus 

 has " a large intestinal and two large gastric spines in the middle 

 line." 



The specimen from Durban agrees with the description of 

 H. spinosus, in that the gastric hump has two spines in the 

 middle line and that there is a spine on the intestinal hump, 

 but they are of insignificant size, the hinder one on the gastric 

 region being hidden in the fur and scarcely even palpable. They 

 do not seem characters sufficient for bestowing specific rank. The 

 carapace, including the straight divergent horns, is 80 mm. long, 

 and, including the lateral epibranchial spines, its breadth is 48 mm. 

 The length of a horn on the free inner margin is 25 mm. The 

 specimen is a female, and the slender chelipeds are considerably 

 shorter than the next peraeopods. 



CYCLOMETOPA. 



FAMILY XANTHID^. 



1898. Xanthidce, (part), Alcock, Journ. Asiat. Soc. Bengal, vol. Ixvii., 



pt. 2, pp. 67, 69. 

 1898. Xanthince (sub-fam.), Alcock, loc. cit., p. 77. 



Alcock defines his family Xanthidae as one " in which the fold of 

 the antennules is transverse or obliquely transverse, and the anterior 

 boundary of the buccal cavern is raised and sharply defined, so that 

 the external maxillipeds commonly shut close against it unless they 



