222 MR. R. I. POCOCK ON A NEW [Mar. 18, 



that the budding groAvth of the bone-core differs in structure and 

 mode of development from the frontal bone proper, but he 

 emphatically doubts the temporary separate existence of the 

 OS cornu, and he feels satisfied that it is not formed by the interven- 

 tion of cartilage, since the substance in question was not coloured 

 blue by hsematoxylin staining. He and others will have to 

 accustom themselves to the existence of cartilage in places whei'e 

 text-books carefully abstain from mentioning it. 



2. On a new Stridulating-Organ in a Scorpion. 

 By R. I. PococK, F.Z.S. 



[Received Febmary 25, 1902.] 

 (Text-figure 26.) 



Stridulating-organs have been found in three geneiu of Scor- 

 pions, viz., the large species of the Oriental Region and Tropical 

 Africa referred to Fcdamnceus and Pandimis, and the South- 

 African members of an allied form Opisthophthal7)ius \ In the two 

 fii-st-named the organ lies between the basal segments of the 

 chelae and of the legs of the first pair ; in the latter between the 

 inner surfaces of the mandibles or their upper edge and the front 

 border of the carapace. In all three cases it consists in the main 

 of peculiarly modified bristles. No organ of similar fvinction has 

 as yet been discovered in any other family of Scorpions. But in 

 the Buthoid genus known as Parahtdhus^ which ranges from the 

 shores of the Red Sea to Cape Colony, I find a stridulator (text- 

 fig. 26, A & B, p. 223) differing entirely both in structure and 

 position from that of the Scorpions above mentioned. 



It has long been known that the upper sides of the proximal 

 segments of the tail in Parahuthus are furnished in the middle 

 with an aggTegation of granules, so fine and close-set as to be 

 appropriately comparable to shagreen. The granules are some- 

 times thickest and coarsest in the median groove, but finer and 

 more scattered at the periphery of the area ; sometimes of 

 uniform strength throughout : sometimes they are confined to 

 the median groove ; sometimes, and more often, they encroach 

 upon the adjacent area of the surface that bears them. 



Of the species known to me, the granulation reaches its highest 

 point of development in Parahuthus jiavidxis Poc, where the 

 granules have run togethei- across the middle line to form short 

 parallel transverse ridges with their free edges directed backwards 

 (text-fig. 26 B). 



The surface that bears this granulation also differs in forma- 

 tion according to the species. In the more northern and less 

 Specialized forms — such as P. liosoma, P. ahyssinicus, P. hunteri, 

 P. granimanus, and P. heterurus — the area in question is but 

 little modified, remaining normally depressed and grooved in the 



1 Pococt, Nat. Science, ix. pp. 17-25 (1896), and Ann. Mag,. Nat. Hist. (6) xviii. 

 pp. 75-77 (1896). 



