Munkittrick.
Butterfly.-Small or medium-sized butterflies, very closely approximating in form and color the species of the genus Argynnis, in which they are included by many writers. The principal structural difference between the two genera is found in the fact that in the genus Brenthis only one of the subcostal nervules arises before or at the end of the cell of the primaries, while in Argynnis the two innermost subcostal nervules thus arise. In Brenthis the palpi are not as stout as in Argynnis, and the short basal spur or branch of the median vein of the front wings, which is characteristic of the latter genus, is altogether lacking in Brenthis.
Egg.—The eggs are subconical, almost twice as high as wide, truncated at the top, and marked with thirteen or fourteen raised longitudinal ridges connected by a multitude of smaller cross-ridges.
Larva.—The caterpillars are not noticeably different in their general appearance from those of the genus Argynnis, except that they are smaller and generally not as dark in color as the larvæ of the latter genus. They feed, like the caterpillars of Argynnis, upon violets.
Chrysalis.—The chrysalis is pendant, about six tenths of an inch long, and armed with two rows of sharp conical tubercles on the back.
[a]Fig. 90.]—Neuration of the genus Brenthis, enlarged.
(1) Brenthis myrina, Cramer, Plate XV, Fig. 1, ♂; Fig. 2, ♂, under side; Plate V, Figs. 12-14, chrysalis (The Silver-bordered Fritillary).
Butterfly.—The upper side of the wings is fulvous; the black markings are light, the borders heavy. The fore wings on the under side are yellowish-fulvous, ferruginous at the tip, with the marginal spots lightly silvered. The hind wings are ferruginous, mottled with buff. The spots, which are small, are well silvered. Expanse, ♂, 1.40 inch; ♁, 1.70 inch.
Egg.—The egg is conoidal, about one third higher than wide, marked by sixteen or seventeen vertical ribs, between which are a number of delicate cross-lines. It is pale greenish-yellow in color.