OCR Text |
Show 1897.] MR. R. I. POCOCK ON ETHIOPIAN SPIDERS. 771 Measurements in millimetres. Total length 22; length of carapace 10, width 9 ; length of 1st leg 35, of 2nd 32-5, of 3rd 31, of 4th 41; patella and tibia of 1st 12*8, of 4th 13"5; protarsus of 4th 12. Loc. W . Africa (Keyserling coll.). T w o male examples. These two examples are the specimens referred to by Karsch (Berl. ent. Zeits. 1884, p. 350) as the males of Dipluraloncgipalpis, Karsch (Zeits. Naturwiss. (3) iv. p. 564, 1879), which was based upon a female from the same area. But the specimens belong neither to the genus Diplura nor yet to the family Dipluridae. Moreover, the evidence that they are in reality the males of the species named longlpalpls is to m y mind somewhat slender. [P.S., July 30th, 1897.-Since this paper was written and read before the Society in the middle of June, I have discovered in some of the African genera of Theraphosinae an organ which 1 believe furnishes a key to their affinities of greater value than those relied upon for grouping them on p. 745. This organ is a curious system of hairs, certainly of a stridulating nature, developed on the anterior side of the upper half of the coxa and trochanter of the 1st and in a lesser degree of the 2nd leg also. In the diagnosis of Hgsterocrates glgas mention is made of a " curious brush of hairs on tbe upper side of the coxa and trochanter" of the limbs in question. W h e n the 1st leg of this species is removed and the organ submitted to closer inspection, under a lens of low power, it will be seen that the so-called brush of hairs consists of a fringe of close-set whitish feathery hairs. On the trochanter this fringe overshadows and probably protects from dirt a number of long, erect, but apically curled stoutish spines arranged somewhat irregularly in two rows. On the coxa the hairs of the fringe become stout and spiniform where, at the base of the segment, they extend downwards towards the coxal suture, and distally some of them become isolated so as to have perfect freedom for vibration. But in addition to these whitish plumose spines there are two long, stout, black, simple spines, the larger being clavate and lying amongst if not above the fringe, the other being situated below it and not expanded at its distal end, but sharply pointed. Below the suture the bases of the upstanding bristles are very stout, black, and shining, while amongst them arise some delicate erect hairs with shining hyaline clavate tips. The large bristles that lie above the suture of the coxa are set in vibration when this segment is rubbed against the adjacent surface of the coxa of the pedipalp, the distal half of which is covered with hairs, amongst which arise a number of long, stout but pointed spines. Similarly, tbe spiniform bristles on the trochanter are rubbed against the posterior aspect of the trochanter of the pedipalp, which is covered with stiff straight hairs. When the spider is allowed to dry after removal from alcohol, the |