XlV INTRODUCTION. 



Still continue, as they formerly were, to be considered as mere va- 

 rieties of one inconstant species. 



Again, Acronycta (another Lepidopterous genus) contains also 

 similar examples ; among which may be pointed out the two well- 

 known insects A. Psi and A. tridens, which approximate so closely 

 to each other in the winged state, and moreover are each subject 

 to such considerable variations, that none but an experienced en- 

 tomologist can reduce all the varieties to their proper species; yet 

 their larvs are singularly dissimilar. 



Many similar exam])les might be cited amongst the Coleoptera, 

 especially among the Protean genus PoeciluSj the species of which 

 are so remarkably alike, and so prone to vary, that even the most 

 acute entomologists err upon the point of their specific differences, 

 from not attending sufficiently to their minutiae. 



It has been observed, that the chief points of specific distinction 

 consist of " form, sculpture, and disposition of colour." But a very 

 slight acquaintance with the works of Nature will show that each 

 of these characters must be handled with the greatest circumspec- 

 tion, as they are all subject to much variation : however, the first 

 is the most stable ; sculpture the next so, though in many of the 

 Coleoptera a considerable deviation from the usual standard takes 

 place, as instanced in the Geodephaga generally *, and more par- 

 ticularly so in Carabus monilis : slight variations of this character 

 also occur in some of the other Orders. Disposition of colour is, 

 however, a most inconstant specific diagnostic, though its various 

 shades and gradations admirably distinguish the larger groups, as 

 I have elsewhere taken occasion to notice, and as Mr. Kirby has 

 indicated amongst the Geodephaga. Do we not, for example, find 

 the Dyticidie characterized by prevalent tints of brown, fuscous, or 

 olive, rarely with metallic shades? and is not the succeeding family 

 (the Gyrinidte) usually of a deep leaden hue, and mostly glossed 

 with ceneous ? and are not the Chrysomelida; eminently distin- 

 guished by the splendour of their brilliant golden or cupreous tints, 

 most frequently upon a green or bluish ground? while in the 

 neighbouring family of Coccinellidae, the species of which seemingly 

 differ greatly in colour, all metallic splendour vanishes, and the 

 only tints of colour which occur are black and white, with various 

 combinations of red and yellow. Numerous other examples might 

 be pointed out, as may be readily seen by an inspection of several 

 of the groups in this Catalogue. There are, however, many spe- 

 cies, especially amongst the Geodephaga and the CrioceridjE, that 

 partake of nearly every colour of the rainbow : Donacia Proteus, 



* The monstrous variations in the sculpture of the elytra, — such as the 

 interrupted confluent stria*, or the rugose crcnulated appearance of the 

 surface, — are clearly not indicative of specific difference, although such has 

 been employed. \'ide Nos. 190, 19(>, &c. 



