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Show 1873.] REV. O. P. CAMBRIDGE ON SIBERIAN SPIDERS. 435 The following papers were read :- I. On some New Species of Araneidea, chiefly from Oriental Siberia. By the Rev. O. P. CAMBRIDGE, M.A., C.M.Z.S. [Eeceived March 15, 1873.] (Plates X L . & XLI.) In M a y 1872 a small collection of minute Spiders, collected by Dr. Dybowski in the neighbourhood of Kuttuk on the southern point of Lake Baikal in Oriental Siberia, was kindly sent m e by Mons. Taczanowski, of the Zoological Museum at Warsaw. This collection was accompanied by two others-one made by M . Taczanowski near Warsaw, the other by Dr. Karpinski at Kiew, in Ukrania. The two last collections number between forty and fifty species, chiefly of the genera Linyphia and Erigone (the latter equivalent to Neriene and Walckenaera, Blackw.) ; but, although some of these species are of great interest, I can detect but one novelty among them (Erigone sollers, postea, p. 443, Plate X L I. fig. 8) ; the rest belong to species already recorded in Northern and Western Europe. In the Siberian collection, however, out of eighteen determinable species thirteen appear to be undescribed :-one of the family Agelenides, genus Lethia (Menge); the rest of the family Theridiides, four being of the genus Linyphia and eight of the genus Erigone. A point of special interest in regard to these new species is their being so exceedingly closely allied to forms already described from northern and western Europe, and yet so curiously and decidedly distinct; while, at the same time, the collection contained neither of the species to which they are thus (severally) so nearly allied. Not knowing what may have been the range or extent of the search of which this Siberian collection is the result, nor the season at which it was made, it is impossible to speak with certainty as to the richness of the locality in respect of these minute Spiders; but the sample now under consideration leads m e to believe that the part of Siberia in question would yield numerous additional and still more interesting forms when carefully searched. Another point of interest with respect to this collection is, that the locality where it was made (Baikal) is the easternmost point at which, as far as I am aware, any species of Erigone has yet been found. Sketches of critical portions of the structure of the Spiders described in the present paper have been added to the descriptions (see Plate XL.) in the hope of making it easier to compare and distinguish other closely allied species. Fam. AGELENIDES. Genus LETHIA. LETHIA TACZANOWSKII, sp. n. (Plate XL. fig. 1.) Adult male, length 1| line. The cephalothorax is of ordinary form ; the lateral constrictions 28* |