OCR Text |
Show 766 REV. O. P. CAMBRIDGE ON NEW ARANEIDEA. [Jliue21, Aphantochilus, Cambr. (P. Z. S. 1870, p. 744). This latter genus was conjectured to belong to the Myrmecidse; but I have now no hesitation in forming for it and the genus Bucranium a separate family (Aphantochilidee), near to the Thomisidfe. More extended remarks on all these points will be found in the subjoined descriptions. Order ARANEIDEA. Fam. THERIDIID^E. Gen. nov. THWAITESIA. This genus is nearly allied to Theridion, but may be easily distinguished by the conically elevated abdomen, the shorter, stronger maxillse, the more prominent ocular area, the larger eyes, which, although preserving a similar general arrangement, are divided into two well separated groups of four each, each group formed by one of the lateral pairs and the hind and fore lateral eye next to it, all four being almost, or quite contiguous to each other; the fore central pair are smallest, and form a shorter line than the hind centrals. The legs also are armed with distinct spines on the genual and tibial joints of all four pairs ; while the metatarsi and tarsi of the fourth pair are armed with numerous spine-like bristles, a row near the inner side of the tarsi being curved and serrated. This latter armature, however, is much less strong in the male than in the female; indeed in the male I could not distinguish any serrations. The relative length of the legs, which are rather long and slender, is, as far as I could judge from the damaged condition of some portions, 4, 1, 2, 3, the difference between those of the first and fourth pairs being but slight. The falces are weak, straight, and subconical, and the fang likewise small and weak. The sternum is heart-shaped. THWAITESIA MARGARITIFERA, sp. n. (Plate LXVI. fig. 1.) Length of the adult male 1| line, that of the female being rather more than 2 lines. The cephalothorax is pale yellow, some examples having an indistinct reddish-brown central line from the occiput backwards; and two (females) had a broad brown central band from and including the eyes to the hinder extremity of the thorax. The thorax is gibbous above, with the thoracic indentation strong; the ocular area of the caput projects forwards, the eyes (disposed as above mentioned) occupying the whole of the upper extremity of the caput; the height of the clypeus considerably exceeds half that of the facial space, and projects well forwards. The legs are similar in colour to the cephalothorax, the articulation of the tibiae and metatarsi of the first and fourth pairs having a tinge of reddish brown, and a portion at the extremities of the metatarsi of these pairs being also dark reddish brown. On the upper side of each of the genual joints is a distinct black spine ; and on each of the tibise are two others, one near the middle and one near the anterior extremity. |