Mr. R. I. Pocock on East-African Scorpions. 427 



Loc. Athi Plains. A single female example. Also two 

 examples of a closely allied though not quite identical form, 

 from Niomkolo, Lake Tanganyika [A. Carson), which are 

 not sufficiently well preserved to be satisfactorily identitiable. 



The genus Bahycurus is of considerable interest from a 

 taxonomic point of view, on account of the position it occupies 

 with regard to the other genera of the Buthidse and the 

 stumbling-block that it constitutes in the way of the adoption 

 of the two classifications of the family that have been pro- 

 posed by Dr. Thorell and by Prof. Kraepelin. The former 

 divided the genera into two subfamilies, the Androctonini 

 and the Centrurini — the former being characterized by the 

 presence of two lower teeth on the immovable mandibular 

 fang, while in the latter there is only one such tooth or none. 

 In my paper on " A Revision of the Genera of Buthidse " * 

 I ventured to suggest that such a classification was untenable f, 

 in view of the discovery of many genera of Buthidse since 

 1876, when Thorell wrote ; and 1 further ventured upon the 

 statement that, in my opinion, the family was not susceptible 

 of division into groups of the value of subfamilies. 



The first opinion is, I think, borne out by the classification 

 proposed in 1891 by Kraepelin, who attributed only a sub- 

 sidiary importance in his scheme to the dentition of the 

 mandible, but regarded the so-called tibial spurs and the 

 dentition of the fingers of the chelae as being of primary value. 

 Taking these two characters into consideration, he split up 

 the Buthidfe (Androctonidte \) into three subfamilies : — 



(1) Androctonini, with a tibial spur on the fourth and usually 

 on the third leg as well ; (2) Isometrini, and (3) Centrurini, 

 the latter difi"ering from the former in having the additional 

 external teeth on the fingers of the chelse. This use of the 

 tibial spurs was, to my mind, a great advance in our know- 

 ledge ; but I do not consider that the difference in the den- 

 tition between Centrums and Tityus is sufficient warrant for 

 referring them to distinct subfamilies. An exactly analogous 



• Proc. Zool. Soc. 1890, pp. 114 &c. 



t To be logically consisteut Thorell sliould, I think, have referred his 

 genera to three categoriejj, namely: — (1) those with two of these teeth ; 



(2) those with but one ; and (3) those with none. For it is difficult to see 

 the grounds for uniting 2 with 3 rather than with 1, since, according to 

 the character cited, it holds an intermediate position between the other 

 two. 



X Thorell, and following him Kraepelin, calls the family Androctonid«. 

 I prefer Simon's name Buthidfe, on the ground that Androctonus is a 

 synonym of Buthtis. 



30* 



