OCR Text |
Show 1 9 0 2 . ] SPIDERS FROM BORNEO AXD SINGAPORE. 261 enjoys is doubtless due to tlie closeness of its resemblance to an equally conspicuous Salius, an ally of which has already been noted as the model of a Longicorn beetle. The fore wing of the Laphria is large, almost as broad as both fore and hind wing together of the Salius and of the same clear golden-brown. The thorax, as in the wasp, is covered dorsally with a golden pubescence, whilst the abdomen, like that of the model, is black, and terminates in a sharp tufted point very suggestive of a sting. All the tibiae and tarsi are ochreous, but the black and thickened femora are very unlike those of the Salius. No attempt at mimicking the long ochreous antennae of the wasp is made, as in some other Diptera shortly to be described (compare figs. 9 & 10, Plate XXII.). The buzzing, noisy flight of this fly is very like that of its model. [In the natural attitude of rest it is probable that the black femora of the fly are held upright and near to the body, so that the ochreous parts of the legs would alone be conspicuous. It is noteworthy that the under sides of the anterior femora are ochreous, suggesting that the anterior limbs may in certain attitudes be raised, or, at any rate, that they are held so that this part is more conspicuous than any other femoral surface. It is probable that this special colouring is directed to meet a view from the front. It is to be hoped that future observations will be specially directed to these points. This fly belongs to the family of the Asilidae (subfamily Laphrince.), the most formidable and predaceous of Diptera, and it is quite possible that the resemblance to a wasp is Miillerian (synaposematic) rather than Batesian (pseudaposematic).-E. B. P.] ii. Mimic. Hyperechia fera (v. d. Wulp). Plate X X II. fig. 2. Model. Xylocopa latipes (Drury). Plate X XII. fig. 1. No more remarkable proof of the plasticity of the Dipterous form could be advanced than this remarkable insect. The large, clumsy Xylocopa, with its bronzy wings and thick furry legs, would seem to be an eminently unsuitable and difficult model to copy ; and it would be most instructive, if only it were possible, to trace the steps by which this fly has arrived at what at first sight appears to be the pitch of mimetic perfection. As a matter of fact the fly is extremely rare, and one can only Conclude that the mimicry, exact though it seems, has failed to preserve the species as a dominant one. The head is characteristically Dipterous; the thorax is of shining blue-black, clothed with a fine dense pubescence, coarser and longer on the sides ; the broad, flattened abdomen is laterally bordered with a fringe of long hairs exactly as is the case with the Xylocopa, and terminates in a fine tufted process suggesting a sting. As in X . latipes, all the legs are remarkably hairy and sturdy, particularly the last pair, and are of much the same length.5 The wings are of a bluish-bronze hue : the downwardly- |