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Show 1880.] OF T H E G E N U S ARGYRODES. 339 The palpi are rather short, the cubital and radial joints particularly so ; the digital joint is large, and in form very like that of A. ululans, being devoid of the prominence so very strongly marked in A. epeirce and others. The palpal organs are simple in structure, but prominent and well developed, with a short, closely fitting, curved black spine near their anterior extremity. The eyes are in the ordinary position ; those of the hind central pair are separated by a wider interval than those of the fore central pair. The falces are neither very long nor strong ; and their direction is a little forwards. The abdomen has its upper part produced backwards into a long, somewhat tapering form, its extremity being slightly and imperfectly trifid, i. e. a blunt angular point on each side below, and a third, rather longer, above and directed rather downwards; its groundcolour is of a dull brownish hue (though, the examples being in bad condition, this may be different in life), marked with a pattern of brilliant silvery spots as represented in fig. 17 ; the hinder part of this pattern meets over the upperside ; there is also a single conspicuous silvery spot almost underneath on each side near the hinder extremity, and another in the middle of the underside a little way in front of the spinners. One tolerably perfect example, and some fragments of others, were found among debris of the web of some large Epeirid, in Prof. Traill's Amazons collection. ARGYRODES AMPLIFRONS, sp. n. (Plate XXX. figs. 17 a', d', e', \7b',c',d',e',f',g,h.) Adult male, length to the spinners scarcely 1 line, and to the apex of the abdomen 1|; in the adult female these measurements are, respectively, £ of a line and rather more than 1| line. This Spider is very nearly allied to Argyrodes obtusa, but may be distinguished by several well-marked differences. The prominence of the lower part of the caput (or inferior lobe) is much larger, still more obtuse; and its upper part, when looked at from in front, is more considerably cleft or bifid ; the space also between the cleft or perforation which divides the lobe aud the fore central eyes is more prominent. The abdomen is more elongated, and more distinctly trifid at its apex; and the silvery markings are merely two small patches of spots on each side, a small spot on each side rather underneath near the apex, another in the middle of the underside a little way in front of the spinners, and two more in a transverse line behind them. The palpi are very like those of A. obtusa ; and the general colouring and appearance of the whole Spider is also very similar. The female has the anterior part of the abdomen much more tumid, more perpendicular in its direction, and its apex more conspicuously trifid; its whole surface is silvery, excepting a longitudinal, not very distinctly defined, central longitudinal band on the upperside extending quite to the apex, and a pointed stripe on the |