3b 



Spcnct Bate separated Pcmachcles from this genus on the 

 ground that in the former all the live pairs of legs in both sexes 

 were more or less perfectly chelate, whereas in Folyclic'cs the fifth 

 pair of the male was supposed to end in a simple finger. It 

 subsequently appeared, however, that species evidently belonging 

 to Puiychclcs had the fifth pair imperfectly chelate in the male, 

 and that in all the species it was chelate in the female- Alcock 

 now supplies a more important distinction, pointing out that in 

 Pentachelcs " the epipodite of the external maxillipeds is of fair 

 size; those of the thoracic legs are normal epipodites ascending 

 into the branchial chamber," but that in Polychclcs " the epipodite 

 of the external maxillipeds is a mere papilla ; those of the thor- 

 acic legs are merely membranous expansions of the base of their 

 podobranchise." When Professor S. I. Smith described the 

 Nova Scotian Polychelcs sculptus he admittt-d that he could not 

 distinguish it from the Figian Pentachcles ajiriculahis, Bate, of 

 which the characters had at that time been only briefly indicated- 

 In his Challenger Report, Bate transferred the latter species to 

 a genus Stcrconiasiis, which, he says, " differs in nothing exter- 

 nally from Pcnlachelcs, but is established to receive those species 

 in which the mastigobranchial lash does not exist." But that, as 

 Alcock now explains, is the very character on which the separa- 

 tion between Polychdes and Pcnlachelcs must best be grounded- 

 Faxon, however, unites .both Pentachcles and Stereomasfis with 

 Polychelcs, remarking that " an examination of a large number of 

 'Species discloses a gradual transition in the development of the 

 epipods, from large, well-developed organs through small, 

 delicate and thin ones, to mere.strudimetits in the shape of small 

 expansions at the base of the stem of the gill-" 



P0LYCHELE.S SCULPTUS, S. I. Smith. 



1880- Polychelcs sculptus, Smith, Proc. U-S. Mus- for 1879, p- 

 346, pi. 7- 



1899. Pentachcles sculptus, Alcock and Anderson, Ann, Nat- 

 Hist-, ser. 7, vol- 3, p. 239- 



1901. Polychelcs sculptus, Alcock, Catal. Indian Deep-Sea Crust- 

 acea, Macrura and Anomala, p- 170. 



Alcock gives the synonymy, which includes Polycheles spinosus 

 A. Milne-Edwards, 1880, and the name Pentachcles sculptus, 

 which has l)een used both by Professor Smith himself and by 

 Alcock and Anderson- The specimen from South Africa closely 

 agrees in all external particulars with the minutely-detailed 

 account given l)y the original describer, except that between the 

 rostral spines and the cervical groove the medi-^n cnrma of the 

 ■carapace has not only i -|- 2 -j- i spines, but an additional spine 

 immediately behind the last of these. In Polycheles phosphorus, 

 Alcock, the part in question carries 1+ i -f 2 + i spines, but 



