126 MR. R. I. pococK ON THE SCORPIONS [Mar. 18, 



and Siiif^apore. But beyoud these limits no species have been 

 recorded'. 



13y the form of the tail the species have been, and may be, divided 

 into two sections. The first is composed of those in which the fifth 

 caudal segment is posteriorly excavated above, and has its infero- 

 lateral keels weakly and uniformly denticulate throughout. Of this 

 group theMuseum possesses examples of the following: — B.hottentota 

 (Fabr.), W. Africa; B. minax, L. Koch, Egypt {=Uicutecurinatus, 

 Simon) ; B. eminii, Pocock, E. Africa ; B. socotreiisis, Pocock, 

 Socotra ; B.jiiduicus, Simon, Syria ; and B. tnartensii, Karsch, India. 

 To the second section, comprising those forms in which the fiftli caudal 

 segment is but slightly, if at all, excavated above posteriorly and in 

 which its inferior keels are irregularly and as a rule strongly 

 denticulate, are to be referred a great number of species, which seem 

 to be more highly specialized than those in the first category. 



Subgenus Prionurus, Ehrb. 

 Prionurus, Hemj)r. & Ehrenb. Verb. nat. Fr. Berlin, i. p. 356 



(1829) — type fmiesius { = uustralis, Linn.). 



Prionurtis, Pcter-s Monatsb. Ak. Wiss. Berlin, 1862, p. 513 — 

 type /unestus {=^austraHs, Linn.). 



Androctonus, Tiiorell, Etudes Scorpio). — type australis (Linn.). 



Not Prionurus, Karsch, Berl. ent. Zeitschr, xxx. (1886) p. 77. 



Hah. N. Africa and Syria. 



This subgenus is closely allied to the preceding, and differs 

 merely in having the lateral margins of the upper surface of the fifth 

 caudal segment compressed and carinate, instead of rounded. The 

 tail is always strong, sometimes exceedingly powerful. 



It is not quite clear as to what is to be tlie name for this group. 



In his work on the Scorpions Ehrenberg constituted the genus 

 Androctonus ; and without definitely naming a type species divided 

 the genus into two subgenera. The first of these — the small-tailed 

 forms — he named ieiwrM*, with the tyjie tunetanus or quinque-sfriaius; 

 to the second or thick-tailed forms he gave the name Prionurus, 

 with the type funesius. When Peters revised the group he concluded 

 that the two sections should constitute genera ; consequently he 

 abolished Androctonus, apparently because it was without a type 

 species ; made, and rightly, Leiurus a synonym of Buthus, but 

 preserved Prionurus as a genus in almost the sense in which the 

 name was used by Ehrenberg. But Dr. Thorell, recognizing that 

 the name Androctonus must take precedence of either one or other 

 of its subgenera and that a type must consequently be fixed upon 

 for it, decided to upset Peters's arrangement and to substitute 

 Androctonus for his Prionurus. 



But according to the system which has been followed, as far as 

 possible, throughout this paper — that is, the system of selecting the 

 first species mentioned under a genus as the type of the genus, when 

 no other is specified — the type of Androctonus is tunetanus. But 



^ Androctonus varicgatiis, Gerv., i'rom New Ireland, is iu all probability au 

 Isometrus. 



