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Show 438 REV. O. P. CAMBRIDGE ON SIBERIAN SPIDERS. [May 6, angulipalpis by tbe form and structure of the sexual aperture, which in L. karpinskii is more prominent and has a long, strongish, curved epigyne, which arches over from the fore to the hinder part; this epigyne is of a pale, semidiaphanous, whitish colour, and is dilated in the middle ; in other respects the female resembles the male. Both sexes of this Spider in the adult state were contained in the Siberian collection received from M . Taczanowski. LINYPHIA DYBOWSKII, sp. n. (Plate XL. fig. 3.) Male adult, lengtb 1\ line. This interesting Linyphia is closely allied to the foregoing and also to L. angulipalpis (Westr.), which it resembles, both in general form, structure, and colour; it is, however, larger and deeper-coloured than L. karpinskii, and may be distinguished without difficulty from both species by the structure of the palpi and palpal organs. In L. karpinskii the cubital joint of the palpus is in fact five-sided when looked at in profile, but in the present it is four-sided ; the profile of the upperside, instead of presenting a somewhat angular, as in L. karpinskii, and a strongly angular gibbosity as in L. angulipalpis, consists of an evenly curved or arched line, from the fore extremity of which, where it forms with the lower side a strong prominence, there springs a strong, tapering, black spine, of a strongly curved, and, in fact, of a sickle form, handle and all being represented. The radial joint is very short, much constricted at its junction with the cubital, and a little produced in front. The palpal organs are well developed and complex, consisting of bolder corneous processes than those of L. karpinskii. The figures given of the palpal organs of this species and L. dybowskii, although generally accurate, must not be relied upon for exceeding accuracy of detail; such minute accuracy, however desirable, could not be obtained under the difficulties under which the figures were drawn. The female of L. dybowskii may be easily distinguished from that of both the other species named by the strikingly different form of the process connected with the sexual aperture. A comparison of the sketches given of that portion of structure of the present species and L. karpinskii will show this at a glance. Both sexes of this species, in the adult state, were contained in M. Taczanowski's Siberian collection, made by Dr. Dybowski, whose name I have taken the liberty to confer upon this interesting Spider. LINYPHIA UNICORNIS, sp. n. (Plate XL. fig. 4.) Adult male, length 1 line. This very distinct and remarkable species has the whole of the fore part (including the legs and palpi, but excepting the sternum) of a clear yellow colour, the sternum being strongly suffused with sooty brown ; the abdomen is of a pale straw-yellow hue, with two longitudinal rows of brown-black blotches on* the upperside, converging towards the spinners, and continued in lateral lines or short |