OCR Text |
Show 334 REV. O. P. CAMBRIDGE ON SPIDERS [Apr. 20, ARGYRODES BICORNIS, sp. n. (Plate XXIX. fig. 12.) Adult male, length to the spinners 1 line, to the apex of abdomen rather more than Inline. It is perhaps questionable whether this Spicier should not be included in the genus Ariamnes (Thor.) rather than in Argyrodes, the two genera being very closely united ; believing it, however, to have more in common with the latter than with the former genus, I have, for the present at least, placed it in Argyrodes. The form of the caput is very striking, and distinguishes it at a glance from all the Spiders of this singular group yet known to me. The posterior lobe (comprising the ocular area) has its centre produced into a strong, horn-like, slightly curved, tapering, obtusely-pointed eminence, directed forward, surmounted with a tuft of long, strong, bristly hairs also directed forwards; immediately below the fore central pair of eyes, at tbe upper part of the clypeus (which slopes considerably forwards), is another horn-like prominence directed forwards in a parallel direction with the other, and of about equal length but not nearly so strong, straight, and slightly enlarged at its extremity, which is also furnished with some long bristly hairs directed rather backwards, so as to meet those directed forwards from the extremity of the posterior horn. The colour of the cephalothorax is pale yellow, with a suffusion of reddish brown on the margins, mostly on that of the thorax. The leys are long and slender, especially those of the first pair; their relative length is 1, 2, 4, 3 ; and they are similar in colour to the cephalothorax ; the tibia?, tarsi, and metatarsi of those of the first and second pairs reddish yellow-brown. They are furnished pretty thickly with fine hairs, many of those on the tibiae being erect. The palpi are similar to the legs in colour, moderately long, the radial and cubital joints short and of equal length; the digital joint is rather small, oval, and yellow-brown, with a small notch or cleft at the extremity; the palpal organs are compact, and neither very prominent nor complex. The eyes of the fore central pair form a line at least as long as the hind centrals, if not rather longer, and each is very near to, but not contiguous with, the fore lateral eye on its side. The four centrals thus form, as nearly as possible, a square. The falces project considerably forwards, and, with the maxillae, labium, and sternum, are similar in colour to the cephalothorax. The abdomen has its upperside prolonged into a long tapering eminence directed a little backwards in a sloping form, the apex being bifid in a somewhat fish-tail form. It is of a dull whitish yellow-brown colour, indistinctly marked on each side at its anterior extremity with a rusty-red-brown hue, and with a suffusion of the same colour on the upperside towards and round the apex; some traces of a similar hue are also visible on the hinder part; and there is a central longitudinal line of the same on the underside. It is very possible that a series of examples would show some variations in the colour and pattern of the abdomen. |