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Show 222 MR. R. i. TOCOCK ON A N E W [Mar. 18, that the budding growth 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 intervention of cartilage, since the substance in question was not coloured blue by hamiatoxylin staining. He and others will have to accustom themselves to the existence of cartilage in places where text-books carefully abstain from mentioning it. 2. On a new Stridulating-Organ in a Scorpion. By K. I. POCOCK, F.Z.S. [Received February 25,1902.] (Text-figure 26.) Stridulating-organs have been found in three genera of Scorpions, viz., the large species of the Oriental Region and Tropical Africa referred to Palamnceus and Pandinus, and the South- African members of an allied form Opisthophthalmtis1. In the two first-named the organ lies between the basal segments of the chela? 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 function has as yet been discovered in any other family of Scorpions. But in the Buthoid genus known as Parabuthus, 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 Parabuthus are furnished in the middle with an aggregation of granules, so fine and close-set as to be appropriately comparable to shagreen. The granules are sometimes 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 Parabuthus flavidus Poc, where the granules have run together 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 formation according to the species. In the more northern and less specialized forms-such as P. liosoma, P. abyssinicus, P. hunteri, P. granimanus, and P. heterurus-the area in question is but little modified, remaining normally depressed and grooved in the 1 Pocock; Nat. Science, ix. pp. 17-25 (1896), and Ann. Mag. Nat. Hist. (6) xviii pp. 75-77 (1896). |