1902.] SPIDERS FROM BORNEO AND SINGAPORE. 263 



wings resplendent with metallic blue sheen, occurs comnionly on 

 the mountains near Kuching. On Mt. Santubong a fly was 

 recently captured affording a close resemblance to the wasp. 

 The body and legs are exactly of the same shade of colour as are 

 those of the wasp ; the wings, though somewhat browner, are 

 more opaque and possess a blue metallic sheen sufficiently 

 deceptive. Their size is large (larger than the fore wing alone of, 

 the wasp), and it is interesting to note the same downward curve 

 of the submedian vein as was found in Hyperechia fera, suggesting 

 the line of junction between a fore and a hind wing. The 

 antennfe are fairly long, though far shorter than those of the 

 wasp. I have not seen this species in the living state, but even 

 as a cabinet specimen it is a remarkable case of deceptive resem- 

 blance (compare figs. 11 & 12, Plate XXII.). 



Specimens of this fly from the Philippines and Tenasserim are 

 in the British Museum collection of Di]3tera. 



V. Mimic. Physocephala sp. (Fam. Conopidas.) 

 Model. Isclmogaster tnicans (Sauss.). 



This example has been selected at hazard from a large number 

 of similar thin-waisted flies, chiefly Syrphidfe and Conopidte, as 

 typical of the method by which the similarly built Eumenidee and 

 Vespidse are mimicked. The first abdominal segment is much 

 attenuated and drawn out, those following are thickened ; the 

 transparent wings are shaded with fuscous on their anterior 

 borders, in accordance with a similar arrangement in the wasp ; 

 the head is the only part which exhibits any of the yellow 

 colouring of the model. 



vi. Mimic. Gen. et sp. ? (Fam. Stratiomyidae, subfam. Raioliio- 

 cerinoi.) Plate XXII. fig. 6. 

 Model. Mesostemis sp. near^^ci^is (Smith). Plate XXII. fig. 5. 



Both species were taken on Mt. Penrissen on the same day, 

 and the similaiity of their external appearance was equalled by 

 the similaiity of their method of flight and action when at rest. 

 The Ichneumon- fly was common enough, and was frequently seen 

 to hover over a plant for a few minutes, then suddenly drop 

 down and pitch on to a leaf, over which it would wall'j:, moving its 

 white-banded antennae up and down with a quick flickering 

 movement. The fly, of which only one specimen was caught, 

 behaved in exactly the same manner; it would hover, then 

 suddenly settle and walk over a leaf on its mid and hind pairs of 

 legs, waving rapidly up and down its long front legs, the tibise of 

 which being black and the tarsi white, most closely resembled 

 the antennae of the Ichneumon-fly. The femora were kept more 

 or less pressed against the ventral surface of the head, so that the 

 sham antenna seemed actually to arise from the correct position. 

 This method of bringing about a resemblance to long antennas is 



