70 MONOGRAPHIA ^GERIARUM ANGLIC. 



something more tlian accident must have induced it. A design, 

 a trace of system, is undeniable ; every pecuHarity of form and 

 colour, possessed by one group, is assumed in so extraordinary 

 a manner by the other. In this country, the tracing of these 

 similarities from indigenous specimens is attended with some 

 diflficulty, owing to the paucity of our species ; yet the similarity 

 between y^JEgeria Apiformis and Cimbex or Sirex, and between 

 Co?iojjia Myopceformis and Tenthredo neglectus, &c. is too 

 obvious to escape the notice of the most cursory and superficial 

 observer. This similarity is one to which the term "analogy" 

 might, with some reason, be applied. Analogy is a term, as I 

 have before stated,*^ generally misplaced, and scarcely ever un- 

 derstood. To be clearly intelligible it ought to mean, a super- 

 ficial shnilaritf/, which fails before the test of distinguishit/g 

 primary characters ;—\w fact, precisely such a similarity as 

 exists between an ^geria and a Tenthredo ; whilst affinity, — 

 a word equally misapplied, — might be defined a positive simi- 

 lariiy in intrinsic characters, whether these characters be 

 derived from either larva, pupa, or imago separately, or com- 

 bine a description of all the three. Analogy extends no farther 

 than to colour, size and general form, — in fact, to those most 

 trivial of all distinctions by which we separate varieties, or 

 perhaps sometimes species. Affinity, on the contrary, is to be 

 ascertained only by a reference to those higher characters by 

 which genera, families, orders, sub-classes, or classes are to be 

 distinguished. Thus the same specific character might answer 

 equally well for a Tenthredo or an /Egeria;^ but no generic, 

 or higher characters could possibly be applied with equal, or 

 with any propriety to a genus of /Egeriida', or a genus of 

 Tenthredinidce. Therefore the similarity between /Egeria 

 and Tenthredo is an excellent instance of analogy, as it ought 

 to be understood; — the relationship between the families is 

 evidently none. 



Of a very different character is the relation between the 

 .Egeriidce and the Sesiidce, which, it will be observed by a 

 reference to the diagram,^ are placed in close contact; yet 



^ Sphinx Vespiformis, p. 47. See also pp. 26, 27. 



f For example, iEgeria aut Tenthredo, Sp. rubro-cingulata. Antenncc nigra 

 nidcnpicem alba: thorax niger, lima lalerali alblda: abdomen nigrum, cingulo rubra: 

 femora 7iigra: tibia nigra, macula extus alba : tarsi nigri : alls hijalinis, vents ?iigris. 



s Sphinx Vespiformis, facing p. Jl. 



