The amount of toil thus saved to the describing naturalist, and to those who wish to name their specimen, the experienced only can estimate. This brevity of specific character is one of Linnæus’s terse and valuable axioms, who limits its length to twelve words. The best examples, I think, that I can adduce in entomology, of valuable and exemplary specific descriptions, is Gyllenhal’s ‘Insecta Suecica’ which contains exclusively a description of Swedish Coleoptera; Gravenhorst’s large monograph of European Ichneumons; Erichson’s elaborate work upon the Staphylinidæ; and our own Kirby’s ‘Monographia Apum Angliæ.’ Their perfection consists in fulfilling thoroughly all the above conditions, for if any doubt exist upon comparing your insect with their descriptions, you may be fully assured yours is not identical. The only drawback to the utility of Mr. Kirby’s book is that he had to deal with insects variable in condition from many causes, and the variable state of the insect that may have to be compared; his description has evidently been made sometimes from a worn specimen, one that had been exposed to wind and weather, and sometimes from an insect in fine condition. Thus it is important that compared insects should be in an identical state to substantiate the comparison,—a difficulty which this family has specially to contend with, as these insects are more liable than almost any others to vary, owing to their specific character depending much upon pubescence, which is extremely subjected to many modifying influences, for the tinges and positive colour of the hair will much vary by exposure, as it is not possible always to capture a bright individual. Taking specific description thus practically in its full and wide sense, it is requisite, for the purpose of avoiding repetition, that all the characters of the superior combinations should be eliminated, leaving it with those only which have not been thus absorbed, which now constitute its sole remaining distinctive specific peculiarities. Every species necessarily contains within itself, every character of every combination in direct line above it, although these have been gradually abstracted to form those several combinations which are arrived at successively in the synthetical ascent. Analytically, species are the last but combining element of all, although their most remote members. The whole system is an ingenious contrivance for breaking down a complex multiplicity of characters, to simplify the means of reaching all the collateral or adjacent species, that we may be able to determine identity or difference.