116 DE. J. E. T. AITCHISON ON THE ZOOLOGY OF 



Length. Breadth. Height. 



Fifth caudal segment 9J 4 3| 



Vesicle 5 3 3 



Aculeus 5 



Humerus 6J 



Bracliium 8 3j 



Manus 6 4 3J 



"Hand-back" 4£ 



Movable dactylus 9 



Immovable dactylus 7§ 



Pecten 6| 



A single specimen, probably a male, was taken between Hari-rud valley and Meshed. 



This Bnthus presents affinities with several species known to me, but appears to be 

 different from all hitherto described. Perhaps its most noticeable peculiarity is the 

 entire absence of keels and of a median depression on the upper surface of the fifth 

 caudal segment — a peculiarity hy which it may be recognized at a glance from such forms 

 as B. martensii (Karsch) and B. confncius (Simon). "With B. arenicola (Simon, Arach- 

 nides, Expl. Sci. Tunisie, p. 51, 1885), however, it is with respect to the form of this 

 caudal segment that B. parthorum appears to be allied ; for in B. arenicola this segment 

 is said to be " supra Icevi, haud canaliculato, nee costato." But the cephalothoracic and 

 caudal costse are much less strongly developed in the Tunisian form. 



Pour species of Biithus have heen recorded from the Caucasus. These are B. eupeus 

 (C. Koch, Die Arachn. v. p. 127, fig. 418), B. cognatus (L. Koch, Kauk. Arachn. in Isis, 

 Dresden, p. 58, pi. i. fig. 7), B. Caucasians (Nordmann, Voy. Puss. merid. iii. p. 731, 

 pi. i. fig. 1), and B. ornatus (Nordmann, torn. cit. p. 732, pi. i. fig. 2). Although analogy 

 would perhaps lead us to expect to find a greater amount of similarity existing 

 between the Afghan and the Caucasian species than between the Afghan species 

 and those of any other locality, no such similarity can he traced. Por B. parthorum 

 may he at once separated from the ahove-mentioned species by sundry well-marked 

 characters. Por instance, in B. eupeus the fifth caudal segment appears to be without 

 denticulations, and the vesicle is thick, with the aculeus curved and short ; in B. 

 cognatus the infero-lateral keels of this same caudal segment are in part strongly 

 dentate, while in hoth B. caucasicus and B. ornatus the aculeus is remarkably short ; the 

 former, in addition, has thirty pectinal teeth, and the latter the complete supernumerary 

 series of granules on the fourth caudal segment, as in B. gibbosus (Brulle). 



6. Buthtjs apghanus, sp. n. (Plate XIII. fig. 4.) 



This species is so nearly allied to B. europceus, Linn. (=occitanus, tunetanus, of 

 authors), the common and well-known S. European and N. African form, that perhaps a 

 comparison between the two will serve as a satisfactory diagnosis of it. 



Cephalothorax. — Anterior keels as in B.enrop&us; the space between tbem quite smooth. 

 Posterior keels converging in front, sinuous, and in contact with the posterior termina- 



