118 MR. R. I. POCOCK ON THE SCORPIONS [MaV. 18, 



it belongs ; moreover quite at the distal end of the digit, the secondary 

 apical tooth of the median rows becomes enlarged, slightly sepa- 

 rated, and constitutes with the original apical tooth a transversely 

 set pair. Thus in this species we clearly see how the arrangement 

 met with in Uroplectes has been brought about. 



Genus Uroplectes, Peters. 

 (Plate XIII. figs. 3-.5, and Plate XIV. fig. .5.) 



Vrox>lectes, Peters, Monatsb. Ak. Wiss. Berl. 1862, p. 512 — type 

 ornatiis, Peters. 



Tityus, Thoreli, Etudes Scorpio!, p. 8 (1876) ; not Titijits, C. Koch, 

 1836. 



Sab. S. Africa. 



This genus is closely allied to the preceding and can only be dis- 

 tinguished from it by the arrangement of the denticles on the chela\ 

 The denticles of the external series are tlie same in the two genera, 

 but the internal series is composed, in Uroplectes, of a series of pairs 

 of teeth. These appear to have arisen, as, indeed, the} have arisen 

 to a less extent in L. Occident alis, by the separation of the apical 

 tooth of each median row and by its subsequent approximation to 

 the enlarged and slightly separated tooth which forms the secondary 

 anterior end of the series distal to the one from which the external 

 tooth of each pair originated. It thus comes about that in tliis 

 genus the internal series appears to have been formed, as has the 

 external series, merely by the outward bending of the anterior termin- 

 ation of tlie median rows. 



Both Uroplectes and Lepreus are found in S. Africa, and I think 

 there is very little doubt that ultimately, owing to the discovery of 

 intermediate forms, all the species will have to be united into one 

 genus Uroplectes. 



The genus Tityus was established in 1836 bv C. Koch upon a S.- 

 American species named Scorpio haliiensis by Perty. 



Clearly, then, bahiensis is the type of the genus Tifi/us ; but since 

 this species is referable to Isometrus of Elireuberg, a name which 

 antedates Tityus, and since a generic name should never be transferred 

 from its type, it follows that Tityus must be a synonym of Isometrus. 

 In years subsequent to 1836 and especially in 18-45 (Lie Arachni- 

 den, xi.) C. Koch referred many more species to his Tifyus. One of 

 these, a S. -African form, T. lineatus, was selected by Dr. Thoreli as 

 the type of his Tityus ; but since this form differs radically from 

 T. bahiensis, it is clear that Dr. Thorell's Tityus is not equivalent 

 to Titj/us as C. Koch originally applied the name. And since this 

 transference of a generic name from one typical species to another ^ 



' I aiu aware that in the Ann. Nat. Hist. 1888, vol. ii. p. 245, in. connection 

 with th3 names Si-arjiio, Hctcroiiu/triiK, and Falanuiaus, I was the advocate of 

 another system. But farther reflection and wider experience has led me to 

 change the view there set forth : consequently I now think that imlmains is and 

 must always be tlie typical species oiHetcromi-trri^. and that \i iMtniofus be con- 

 generic with africa)ius,X\ie-a 7/c/(';-0//(ci;r«.s must be synonymous ^ith Srorpio,ar\A 

 that in no case can the generic name Hctcriuiietrm be transferred from its type 

 pabnatus to the second species s-jjinifcr, which is consequently a Pcdamneus. 



