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Show 1874.] REV. O. P. CAMBRIDGE ON N E W DRASSIDES. 371 Ceylon), eight are European, one South-American, and one North- American. The larger number were intended to have been included in Dr. L. Koch's work on the Drassides (' Die Arachniden-Familie der Drassiden,' Niirnberg, 1866); but that work having long since been discontinued before its completion, I have thought it best not to delay their publication any longer. M y thanks are especially due to Dr. Koch for the kind readiness with which he has placed at my disposal all the dissectional drawings made from the type specimens for his own work; these, supplemented with a few others drawn by myself, form the materials of the Plates intended to illustrate this paper. It will be observed that almost all the drawings are taken from portions of the genital organs-the palpi in the males, the genital aperture in the females. The form and structure of these parts afford the best, and in some instances the sole reliable, criteria for the determination of the species. The constant value of the palpi and palpal organs of male spiders for this purpose was first pointed out by our veteran araneologist Mr. John Blackwall; and it has since been abundantly recognized by all araneologists of any note, though, as far as I am aware, the credit of its discovery has not been sufficiently awarded by continental writers to its discoverer. The form of the genital aperture in female spiders as a specific character was first, I believe, made use of by Dr. L. Koch in the work on the Drassides above mentioned ; and it seems likely to prove a most valuable differential character with respect to the females of other groups as well as that of the Drassides. In regard to them especially, it is not too much to say that, but for this character, many species would be quite indeterminable, from their great similarity in general form and colour to others nearly allied. And the same remark applies to the males also, many of which are with great difficulty recognizable as distinct species, except by the form and structure of the palpi and palpal organs. The Drassides are a very plainly coloured sombre-looking group; but few present any marked pattern or colouring ; and in the absence of these a well-defined and easily observed structural character is peculiarly valuable. It is perhaps hardly necessary to say here that these sexual and, as observed before, so strongly specific characters are not developed either in the male or female spiders until the last moult or change of skin, when they become adult. Family DRASSIDES. Genus GNAPHOSA, Latr. G N A P H O S A H A R P A X , sp. n. (Plate LI. fig. 1.) Adult male, length 2f lines. This Spider is of ordinary form. The cephalothorax is broad oval, most pointed before, and somewhat depressed ; the profile slopes gradually in a curved line from the thoracic junction to the eyes, and the lateral constriction forwards is but slight; its colour is yellow-brown with blackish margins ; the normal grooves and in- |