COLLECTED IN THE HADBAMAUT, SOUTH ARABIA. 293 



inner row are situated much further forwards than in B. di- 

 midiatm. (Compare also Thorell, Bull. Soc. Ent. Ital. xxv. p. 364, 

 1894.) 



BUTHUS DIMIDIATUS, SimOfl. 



Buthus dimidiatus, Simon, Ann. Mus. Genova, xviii. p. 244, pi. viii. fig. 17 

 (1883). 



Log. Hadramaut. 



This species was originally recorded from Tes (Taez) in Arabia. 

 The British Museum also has examples from Perim Island (J. J. 

 Walker andE. W. Oates). The examples from this island which 

 were obtained by Mr. Walker were formerly identified by me 

 (Ann. & Mag. Nat. Hist. (6) viii. p. 241) as B. scaler (Hempr. & 

 Ehrenb.); and I am still of opinion that the reference may in the 

 end prove to be correct. But since the figure of Ehrenberg's 

 type specimen does not quite suit the Perim examples, inasmuch 

 as tbe trunk is represented as pale and not olivaceous, I consider 

 it advisable, until genuine specimens of-S. scaher from Arkiko come 

 to hand, to look upon the latter provisionally as a distinct species. 



The name dimidiatus which I formerly doubtfully applied to the 

 Perim specimens I now think is unquestionably the right title 

 for them ; for the characters in which dimidiatus appeared to 

 differ from the Perim examples — namely, in the granulation of 

 the vesicle and tbe parallelism of the sides of the tail — I now 

 discover are characteristic of half-grown specimens, but are 

 more or less obliterated in the adult. Eull-grown specimens of 

 this species attain a length of about 75 mm. ; they then present 

 the colouring described by Simon for his examples, and have the 

 anterior segments of the tail very wide, much wider than the 

 posterior, with strongly convex sides, the width of the first being 

 about equal to the length of the third and much greater than its 

 own length. But in two young examples from the Hadramaut 

 Valley measuring about 35-38 mm., the tail is much more parallel- 

 sided, the anterior segment is not noticeably convex at the sides 

 and is only as wide as long, and the granulation of the lower 

 surface of the vesicle is much coarser than in the adult. They 

 thus closely agree with Simon's example, which measured 49 mm. 

 But they present the further interesting difference in having the 

 whole of the trunk pale, except the anterior part of the carapace, 

 which is blackish green ; and the hands and digits, instead of 

 being pale, are also blackish green. 



