( cxcviii ) 



like most i^ secondary characters, it is in some way an adaptation 

 facilitating pairing. The colours of the face, front-legs, etc., 

 would be those which would be most prominent in the aspect of 

 a ^ approaching a $, while those of the abdomen Avould display 

 themselves more conspicuously to most of the insect's possible 

 enemies — for nearly all these would attack it from above and 

 not from hi front. Whatever be the exact impression produced 

 on the feelings of an Andre7ia or Prosopis $, as she witnesses 

 the approach of her bright-fronted suitor, whether actual 

 admiration or merely surprise and curiosity, it is at least 

 probable that her notice would be attracted by the spectacle, 

 and that thus, so to speak, the ice would be broken, and the 

 road paved for further overtures. 



While both in Fossors and true Wasps yellow and other 

 bright markings on the integument of the abdomen are 

 extremely frequent, they are decidedly unusual among Palae- 

 arctic Bees, except in particular Genera (e.g. Anthidium and 

 its Parasite Stelis, Nomada — also a parasitic Genus, — Campto- 

 poeuw, and Nomioides). Much more frequently in this Family 

 striking colour-characters are produced, not by the integument 

 (which is commonly immaculate), but by the Pilosity, and as 

 to this two general remarks may be made, (1) that in Aculeates 

 bright and conspicuous colours appear as a rule either in 

 the integument or the pilosity hut not in both at once, and (2) 

 that to a certain extent corresponding types of coloration are 

 produced by these two methods, and probably have the same 

 bionomic value. Professor Poulton lately exhibited at a 

 meeting of our Society a remarkable case of two Australian 

 Bees, a Prosopis and a Halictus, with a similar and very 

 characteristic coloration, produced in the one case by integu- 

 mental pigments, and in the other entirely by the Pilosity. 

 Other if less perfect examples of this sort of mimicry might 

 be pointed out in all groups of Aculeates. Thus, while in 

 some Crabronidae and Andrenidae the $ clypevis is made white 

 or yellow by pigmentation of the chitin, in others the same 

 effect is simulated by a clothing of silvery or golden hairs. 

 The abdomen of Bomhius lapidarius is made red-and-black by 

 hairs only, that of Sphecodes gibbtis or Andrena scita by colours 

 in the actual integument. Patterns of white or yellow spots, 



