I am scarcely warranted in attempting a detailed table of this genus, because a number of species are known to me only by a single sex; but in looking over the material, it can be readily perceived that there are two sections, the first represented by quercus, oregonensis and depressus, being characterized by great sexual differences in the mandibles, and the second, represented by all the other species, having the mandibles unmodified in the male. The second section may be divided into three groups: the first, represented by Agassii, pacificus and parvicollis, which, judging by analogy, have the hind tarsi long and slender in both sexes; the second, composed of californicus and thoracicus, having the hind tarsi short, at least in the female; and the third, with stout and triangular tibiæ, at present represented by Keeni alone.