OBTAINED IN EGYPT AND THE SOUDAN. 307 



cataract). A single specimen was obtained at each of the five 

 first-mentioned places, and 17 at the last. This long series from 

 one spot is peculiarly interesting, inasmuch as it clearly shows the 

 characters of the species at all stages. 



The largesL example that I have seen is a $ from Assouan 

 measuring 94 mm. The smallest specimen, from the S.W. Bank 

 of the Suez Canal, measures 27 mm., and the largest (S) about 

 83. The species is entirely pale yellow at all ages, thus differing 

 from the two forms mentioned above as lihycus and priamus. 

 The tail in young forms is quite like that of the genus Buthus, 

 the upper surface of the 5th segment being flat and the angles 

 squared, though granular. This is even the case in specimens 

 of about 60 mm. in length. Moreover, even in examples of 

 this size the tail is narrowed from base to apex, the 1st segment 

 being slightly wider than the 3rd. 



In adult examples of both sexes the 3rd segment is slightly 

 wider than the 1st, the 1st and the 4th being about equal in 

 width, and the 5th distinctly narrower than the 1st, The superior 

 caudal crests are elevated, but the strong elevation so character- 

 istic of lilycus and hector is noticeably absent. Consequently 

 the posterior segments of the tail are very narrow and low as 

 compared with those of lihycus and hector. Lastly citrinus may 

 be also recognized from the two last-named by its very much 

 straighter aculeus. The young again difi'ers from the young of 

 lihycus in having the digits of the chelae shorter and much 

 straighter. In this character as well as in the thinness of its 

 tail these young examples offer a striking resemblance to adults 

 of Huthus leptochelys. 



Peionueus bicoloe, Hempr. Sf Ehrenh. 



Prionurus bicolor, Hempr. 8f Ehrenb. Verh. nat. Freunde Berlin, i. 

 p. 358 (1829) ; lid. Symb. Phys., Scorpiones, no. 9, pi. ii, fig. 4. 



Specimens were brought from the following localities : Cairo, 

 Eamleh, Manadra, Aboukir, andMersa Matroo (150 miles W. of 

 Alexandria) ; but the species is evidently not so common in 

 Egypt as the " yellow " Scorpions. 



All systematists of late years who have worked at Scorpions 

 (including more especially Simon, Thorell, and Kraepelin) have 

 identified this Egyptian species as crassicauda of Olivier, with the 

 name hicolor as a synonym. But all the evidence upon which I can 

 lay ray hands shows that crassicauda of Olivier is quite a different 

 species, which does not occur in Egypt at all. It is true that Olivier 



