3t> 



Spence Bate separated Pentacheles from this genus on the 

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

 were more or less perfectly chelate^ whereas in Polycheles the fifth 

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

 subsequently appeared^ however, that species evidently belonging 

 to Poiychelcs 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 imiportant distinction, pointing out that in 

 Pentacheles " 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 Polycheles '' 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 Polycheles sculptiis he admitted that he could not 

 distinguish it from the Figian Pentacheles auriciilatns, 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 Sterconiastis, which, he says, " differs in nothing exter- 

 nally from Peniachelcs, 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 Polycheles and Pentacheles must best be grounded- 

 Faxon, however, unites .both Pentacheles and Siereomastis with 

 Polycheles, 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 merestrudiments intheshapeofsmall 

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



Polycheles sculptus, S. I. Smith. 



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

 346, pi. 7- 



1899. Pentacheles sculptus, Alcock and Anderson, y\nn. Nat- 

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



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

 acea, Macrura and Anomala, p- 170. 



Alcock gives the synonymy, which includes Polycheles spinosus 

 A. ]\[ilne-FMwards, 1880, and the name Pentacheles sculptus, 

 which has been 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 by the original describer, except that between the 

 rostral spines and the cervical groove the medi?n carina of the 

 ■carapace has not only i + 2 -f i spines, but an additional spine 

 immediateh- behind the last of these. In Polycheles phosphorus, 

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



