Polycheles, Heller. 



Pohjcheles, Heller, 1862. Polycheles, Heller, 1863. Poly- 

 cheles, Bate, 1888. Pentacheles, Bate, 1888. Siereomastis> 

 Bate. 1888. Polycheles, Faxon, 1893. Polycheles, Faxon » 

 1895. Polycheles, Alcock, 1901. Pentacheles, Alcock, 1901- 

 Polycheles, StebbJng, 1903. Polycheles, Bouvier, 1905- 

 Polycheles, Kemp, 1912. 



In his report on the Hacrura of the Challenger Expedition 

 Spence Bate distributes the species of this group among three 

 genera, Polycheles, Pentacheles, and Stereomastis . In Penta- 

 cheles all five pairs of pereiopods were chelate, and in Polycheles 

 only the first four pairs. Faxon, however (1895), showed that 

 this character was useless as some of the species included in 

 Pentacheles had the fifth pereiopods chelate in the female and 

 simple in the male. Stereomastis was founded for the reception 

 of these species in which " the mastigobraiichial lash does not 

 exist." After the examination of a large amount of material, 

 Faxon was able to state that the epipodites of the thoracic legs 

 were to be found in all grades of development, from large 

 structures extending far up into the branchial chamber, to the 

 merest rudiments. He therefore united the three genera in one, 

 and has been followed by the majority of recent writers. Alcock, 

 however, revived (1901) the genus Pentacheles, separating it from. 

 Polycheles by the following characters. 



" Epipodite ... of ths external maxillipedes is repre- 

 sented at most by a papilla. Epipodites are present on the 

 first four pairs of thoracic legs, but they are only mem- 

 branous expansions of the base of the podobranch, and 

 ascend little or not at all into the branchial chamber. — 

 Polycheles, 



External maxillipedes carry a functional epipodite, and 

 the epipodites of the first four pairs of thoracic legs are 

 independent plates, attached to the podobranchiae at the 

 base only, and ascending into the branchial chamber in 

 normal fashion. — Pentacheles.^^ 



But this was merely employing again the character which 

 Faxon had shown to be useless for the distinction of Stereomastis. 

 Moreover, Kemp has shown (1912) that Alcock's species 

 Pentacheles hextii is a synonym of Polycheles typhlops. The 

 characters given by Alcock, therefore, though doubtless holding 

 good for Indian species, cannot be applied to the group as a 

 whole. Polycheles is used in the present paper as including 

 the three genera described by Spence Bate. 



The carapace is nearly as long as the abdomen, and is very 

 much flattened dorsally. The lateral edges are very well de- 

 fined, and are lined with strong broad spines or teeth, the 

 number of which varies with the species ; the edges are slightly 



