246 [September 



resembles in our eyes the insect it preys on, and the fact of the hun- 

 dredth parasite being alike may well be attributed to chance, or to 

 speak with more precision to the genetic connection between all Annu- 

 lata. If '■ imitative" forms only occurred in parasitical families in 

 such species as prey upon the species which they imitate, there would 

 be more plausibility in the common hypothesis ; but it is not so. Co- 

 iiops sayittaria Say, as Harris has remarked, {Inj. Jan. p. 611,) 

 " might almost be mistaken for a Eumenea,'' and in the shape of its 

 abdomen Goaopa also recalls the fossorial genus Tri/poxi/loti and the % 

 of the Evaniide genus Pdecinus. But instead of Gonop.t being para- 

 sitic upon Eumcnes or Trjjpoxi/lo)i^ or Peleciniis, all known Conops are 

 parasitic upon the very dissimilar family of bees and especially humble- 

 bees, with the exception of two species, which are parasitic upon 

 fossorial wasps, but not upon Trijpnxylon or Eumenex, but upon 

 Pompilm and Odijnerus^ to which they bear but small resemblance. 

 (West. hitr. II. p. 560-1. Saunders Trans. Ent. Soc. Lonion, n. s. 

 Vol. 4. PI. 28. St. Farg. Hjjmen. I. p. 45i3.) Again, it was long 

 ago remarked that the Dipterous genus Sij^tropxis strongly resem- 

 bles the Hymenopterous genus Ammophila., and so it certainly does. 

 (West. Jntr. II. p. 543.) But Si/stropua mace)- Lw., or as I wrongly 

 named it Conops analis? Fabr., instead of being parasitic on Am- 

 mophila, as the common theory would lead us to suppose, is para- 

 sitic, as I have shown, on an insect that is altogether unlike a Systro- 

 pus, and does not even belong to the Order Hymeuoptera but to the 

 Lepidopterous Heteroeera. (See my Paper Proc. B. S. iV. //I, Feb. 

 1864, p. 300.) 



When I here speak of parasitic insects, I distinctly exclude those 

 which are sometimes called parasites, but more correctly Inquilines or 

 Gruest-flies, such as the inquilinous Cynipidre, certain inquilinous Ceci- 

 domyia of which I shall have moi'e to say on a future occasion, the 

 Apide genus Coelioxys and the Bombide genus Apathus. (See my 

 Paper on Cynipidie, Proc. Ent. Sue. Pkilad. II. p. 478.) Here re- 

 semblance of form and color is accompanied by a close systematic affin- 

 ity, which is scarcely ever the case with the true Parasites. Hence I 

 conceive it to be perfectly po.Hsible that the Bomhus may mistake the 

 Apathus for an individual of its own species, but that it can so mistake 



