the Systematics of Scorpions. 369 



and inferior laterals smooth, except on the fourth, where 

 they are weakly denticulated or crenate, and on the fifth, 

 where they are distinctly denticulated ; intercarinal spaces 

 smooth ; vesicle much wider than high, as wide as the third 

 caudal segment, serially granular below and laterally. 



Chelce : humerus with superior and anterior denticulate 

 crests, a few scattered coarse granules on the uppcrside ; the 

 lower side with a series, sometimes partially double, of coarse 

 granules along the posterior border ; lower side of brachium 

 with three rows of setal pores posteriorly, the anterior crest 

 of the lower side denticulate, the posterior smooth, the ante- 

 rior surface minutely granular, with one large denticle, the 

 posterior surface pitted with coarse punctures, but smooth; 

 the superior crest crenate ; hand very wide, its width equal 

 to the median length of the carapace and a little shorter 

 than the movable fmger, its upperside punctulated, smooth, 

 with a sculpturing of low smooth anastomosing ridges, nearly 

 obsolete in the middle, but becoming coarser and more tuber- 

 cular towards the inner edge and externally above the smooth 

 keel of the underhand ; inner edge of hand widely rounded, 

 not much produced posteriorly, and strongly dentate in the 

 middle, the denticles becoming smaller towards the base of 

 the immovable finger and posteriorly, the whole of the poste- 

 rior border of the lobe smooth ; underside of the hand with 

 a few scattered denticles and a pair of weakly denticulated 

 keels ; no large tooth on the fingers. 



Legs with two external protarsal spines on the first and 

 second, one apical on the third, and none on the fourth; 

 tarsal lobes armed with four spines, one of which is apical, 

 the total number of spines on the tarsi being five in front 

 and seven or eight behind, the larger number being upon 

 the third and fourth legs. 



Pectinal teeth 21-22. 



Measurements in millimetres. — Total length 98 ; carapace 

 17 ; tail 53 ; width of hand 15, length of underhand 9"8, of 

 movable finger 16. 



Loc. Al-khaur, in the Abian country, 80 miles east of 

 Aden, in Arabia. Collected by Mr. A. B. Percival. 



Apparently most nearly resembling the Somaliland. species 

 P. meidensis of Karsch in the sculpturing and crests on the 

 upperside of the hand and the presence of only a small 

 number of granules on the posterior underside of the 

 humerus ; but in meidensis there are four rows of setal pores 

 on the underside of the brachium and two more spines, one 

 on each side, upon the tarsi of the legs. The other Arabian 

 species, P. arabicusoi Kraepelin (Jahrb, Hanib. Wiss, Anst. 



