General Catalogue of South African Crustacea. 315 



Gen. HEXAPUS, de Haan. 

 1835. Hexapus, de Haan, Crustacea Japonica, decas secunda, p. 35. 

 1900. H., Alcock, Journ. Asiat. Soc. Bengal, vol. Ixix., pt. 2, p. 329. 



Four genera are assigned by Alcock to his sub-family Hexapo- 

 dinae, namely, Hexapus, de Haan, Amorphopus, Bell, 1859, Thau- 

 mastoplax, Miers, 1881, and Lamhclophcdhis, Alcock, 1900, each 

 established for a single species, of which in each case only the 

 male sex appears as yet to have been described. They all agree 

 in the remarkable absence of the last pair of peraeopods, unless 

 a microscopic tubercle described by Bell for his AmorpJiopus can be 

 supposed to represent a leg. Bell reproaches Fabricius and de 

 Haan for finding " nothing special or abnormal in a Decapod having 

 only six pairs of legs besides the claws," although Fabricius by the 

 specific name and de Haan by the generic alike emphasise the fact, 

 and de Haan is careful after his definition to make the further 

 remark, " beyond the six hinder feet, no indication of a fifth pair, 

 nor are any hidden under the pleon.'" It is an obvious slip 

 of the pen on Bell's part when he writes "six pairs of legs," 

 instead of six legs or three pairs. There seems little justification 

 for the separation either of Amorphopus or Thaumastoplax from 

 Hexapus. Miers distinguishes his genus from it "by the much 

 greater development of the second ambulatory legs and the struc- 

 ture of the outer maxillipedes." But he is evidently basing the 

 first of these distinctions on a misunderstanding of the text of 

 de Haan's work, and the second on a figure which is too small 

 to be trusted. In 1886 Miers includes Xenophthalmus, White, and 

 Asthenognathus, Stimpson, among the Hexapodina?, but from Stimp- 

 son's posthumous treatise it may be inferred that the former, and it 

 is made certain that the latter, has the normal number of feet. 



Lamhdophallus is distinguished from Hexapus by the lambda- 

 shaped arrangement in the anterior pair of male sexual appendages 

 — a feature which could not have been overlooked by de Haan, had 

 it been present in the male of Hexapus. 



Hexapus sexpes (Fabricius). 



Plate XLI. 



1798. Cancer sexpes (Fabricius), Suppl. Ent. Syst., p. 344. 



1835. Hexapus s., da Haan, Crustacea Japonica, decas secunda, 



pp. 35, 63, pi. 11, fig. 6 (not pi. 9, fig. 5, as stated in 



text). Hexapus latipes on pi. D. 

 1859. H. s., Bell, Journ. Linn. Soc, vol. iii., p. 29. 



