The eggs of butterflies are very interesting objects. As a rule, those of each natural genus (I speak of the North American fauna, for I know nothing of the eggs of tropical butterflies), are closely alike, as in Pieris, Anthocharis, Colias, Terias, Callidryas; and so, while each genus has peculiarities of its own, there is a family resemblance between these genera (of the sub-family Pierinæ). They are all of one general shape, long, slender, sub-conic, or spindle-shaped, set on end, but differently ribbed according to the genus. So the eggs of Danais and Heliconia and Agraulis each have their own pattern. A11 Argynnis eggs, whether of the large or small species (Groups 1 and 2), are thimble-shaped. On the other hand, Euptoieta, by its egg, is allied to Argynnis, while by the chrysalis, it is allied to Melitæa. It links the two genera, and in my Catalogue of Di. Lep., I place it between these two, instead of before Argynnis, as has usually been the arrangement. So Melitæa, Phyciodes, Limenitis, Apatura, Paphia, Satyrus, Neonympha, Chionobas, may all be distinguished as readily by the eggs as by the butterflies. Lycæna, Lemonias, Thecla, Chrysophanus, so far as I know them, all show generic peculiarities in the egg stage. So does Papilio, though some of the species, as Philenor and Cresphontes, have the surface covered with a rough crust, the usual type being smooth-surfaced.