658 I'UOCEEDIMGS OF THE XATIOXAL MUSEUM. vol.xx.. 



species is inncli nearer to tliat which ai)])ears in Zanzibar than to that 

 of either Kanierun or Lagos. The characters referred to are, as in 

 Diplopoda generally, those of the copulatory legs, more esi)ecially the 

 posterior pair, in the structure of which the present groui) of species 

 differs from its nearest relatives and constitutes a distinct genns which 

 may be called Pachyholus^ the type being a new East African species 

 P. tectus. 



Genus PACHYBOLUS Cook. 

 VachijhoJiix Cook, HraiHltia. 1897, i>. 73. 



African Anocheta of very large size, with a long cylindrical body and 

 a thick exoskeleton. 



Antenna' sliort and thick, accommodated by a cavity in the sides of 

 the head and partially covered by the first segment; olfactory cones 

 numerous. Lahrum with setiferous ininctations. 



Anterior segments with the ventral parts greatly thickened, concave. 



Legs with two ])enultimate joints subequal; last Joint with a broad, 

 oval, concave callus which does not extend beyond a jiair of stont snb- 

 apical bristles. 



Oo]nilatory legs with a large sternum mesially projecting ventrad 

 and usually carinati'; posterior i)air of copulatory long, curved, strongly 

 chitinized. 



The type of the genus is 7*. tectus from Zanzibar and its nearest rela- 

 tive is JIadroholus, a genus based on Spirobolus cras,siro1li.s Peters. The 

 relationship is perhaps too close, but there are several differences of 

 considerable imi)ortauce, Pachubolus being separable from HaiJroholus 

 by the distinct median process of the sternum of the copulatory legs, 

 the approximate posterior lamella* of the anterior copulatory legs, 

 and the longer and distally more strongly chitinized liagella or posterior 

 copulatory legs, which also emerge at the side of the apex of the pos- 

 terior lamella, and have the seminal opening large and surrounded by 

 a membranous fringe. The legs of males of liadroboluH have the last 

 joint longer and the penultimate joint shorter than in I'dchyhoha, and 

 the lleshy sole produced beyond the pair of subapical bristles, while in 

 Pachybolus the sole is broader and does not extend beyond tlie bristles. 

 The two genera are siniihir in habit and color pattern, but Pacliybolus 

 is larger, more robust, iind more heavily armored. 



ANALYTICAI, KKY lO THK .Sl'KCIKS OF I'ACM YIJOLUS. 



Posterior lamina of anterior copulatory legs with a deep notch at the lateral side 

 of the base of the slender apical i)rocc8s; liagella with a large subapical perpendic- 

 ular tooth and a large leaf-like ])ro(es8 sonic distance below the tooth : /'. lainiiuihi.s, 

 new species, Liberia. 



Posterior lamina entire, more or less gradually narrowed to a much hroa«ler apex, 

 llagellum without perpendicular tooth or i.iminate process 1 



Flagcllum slender, attenuate and strongly recurved: /'. lifitdaiuH, T.agos 



Flagellum distinctly more robust and shorter, not attenuate and not recurved in 

 more than a semicirch^; <a])ex broail. Hat. simple, or <'omplicate 



