262 MR. R. SHELFORD ON MIMETIC INSECTS AND [NoV. 4, 



curved submedian vein in the wing of the fly represents the 

 junction between the fore and hind wings of the bee, and the areo- 

 let of the hind-Aving of the bee also finds its parallel in the 

 alula of the fly. The halteres are quite concealed amongst the 

 hairs on the sides of the thorax. I have only seen one solitary 

 specimen of this fly (Kuching, Feb. 1899), and have nothing to 

 record of its habits beyond stating that both on the wing and at 

 rest it was exceedingly difficult to distinguish from the common 

 A', latipes (compa,re figs. 1 & 2, Plate XXII.). 



[It is possible that the fly is constantly mistaken for a Xylocopid, 

 and that it is not nearly so rare as it appears to be. The genus 

 is widespread, and Mr. G. A. K. Marshall has sent me an equally 

 beautiful example from Mashonaland. In this case the insect 

 is unique (it has been recently described as Hyperechia viarshalli 

 (Austen)), but Mr. Marshall's notes clearly indicate the reason of its 

 rarity. It must be remembered also that the extreme perfection 

 of the resemblance is aided by the rapid flight and alertness of the 

 fly. Hyperechia belongs to the same family and subfamily as the 

 species last described, and here, too, the Miillerian interpretation 

 mvist be taken into account. In fact Mr. Roland Trimen, to 

 whom I showed the African specimen, expressed the opinion, from 

 his experience of its allies, that it is a far moi-e formidable insect 

 than its model. The strengthening and curvature of the sub- 

 median vein in the fly's wing, which apparently represents the 

 junction between the bee's fore and hind wings, is an instance of 

 the attainment of a detail in the resemblance by a very slight 

 alteration of form ; for the vein in the last-described species of fly 

 pursues neai-ly the same curved direction, although the line of 

 junction of the wings of its model is nearly straight. In both 

 species of fly there is a slight bi-eak in the even contour of the 

 mai'gin at the point where this vein reaches it, which is very 

 suggestive of a junction between foi'e and hind wings, while the 

 curve of the margin is changed on either side of the break in such 

 a manner as further to promote the resemblance. — E. B. P.] 



iii. Mimic. Milesia vespoides (Wlk.). Plate XXII. fig. 14. 

 Model. Vespa cincta {Fah.). Plate XXII. fig. 13. 



The large wasp, black with a broad red band on the second 

 abdominal segment, is closely mimicked by an equally large fly 

 with the distal half of the second segment and the proximal half 

 of the third segment coloured red. This red band, though 

 actually occupying a different position from that of the wasp, is 

 separated from, the thorax by a black interspace nearly equal in 

 breadth to the wasp's first abdominal segment, which is also black. 

 The wings are similarly coloured in both species (compare figs. 13 

 & 14, Plate XXII.). 



iv. Mimic. Midas, ii. s]). (Fam. Midaida^.) Plate XXII. fig. 12. 

 Model. Macromeris violacea (yLe]}.). PlateXXII.fig.il. 

 Macromeris violacea, a dark blue fossorial wasp, with dark blue 



