_Butterfly._--Dark gray on the upper side in both sexes. On the under side the figure in the plate gives a correct representation of the color and markings. Expanse, 1.10 inch. _Early Stages._--Unknown. The species occurs in northern California, Utah, Nevada, Oregon, and Washington. (2) =Lycæna heteronea=, Boisduval, Plate XXXI, Fig. 13, ♂; Fig. 14, ♀; Plate XXXII, Fig. 19, ♀, _under side_ (The Varied Blue). _Butterfly._--On the upper side the male is blue, the female brown. On the under side the wings are white, with faint pale-brown spots on the hind wings and distinct black spots on the fore wings, more numerous than in _L. lycea_, which it closely resembles on the under side. It is the largest species of the genus, and the female reminds us by its markings on the upper side of the females of _Chrysophanus_. Expanse, 1.25-1.40 inch. _Early Stages._--These await description. _Heteronea_ ranges from Colorado to California, at suitable elevations among the mountains. (3) =Lycæna clara=, Henry Edwards, Plate XXX, Fig. 26, ♀ (The Bright Blue). _Butterfly._--The figure in the plate is that of the type of the female, the only specimen in my collection. Expanse, 1.15 inch. _Early Stages._--These are entirely unknown. The type came from southern California. (4) =Lycæna lycea=, Edwards, Plate XXXII, Fig. 18, ♂, _under side_ (Lycea). _Butterfly._--The perfect insect is very nearly as large as _L. heteronea_. The male is lilac-blue on the upper side, with the margins dusky. The black spots of the under side do not show through on the upper side, as in _L. heteronea_. The female is dusky, with the wings shot with blue at their bases, more especially on the fore wing. There are no black spots on the upper side of the wings in this sex, as in _L. heteronea_. On the under side the wings are whitish. The spots on this side are well delineated in our figure in Plate XXXII. Expanse, 1.30 inch. _Early Stages._--These await description. The butterfly is found in the region of the Rocky Mountains, from New Mexico to Montana. (5) =Lycæna fulla,= Edwards, Plate XXX, Fig. 24, ♂; Fig. 25, ♀ (Fulla). _Butterfly._--Smaller than the preceding species. The upper side of the male is not lilac-blue, but ultramarine. The female is almost indistinguishable on the upper side from the female of _L. lycea_. On the under side the wings are pale stone-gray, with a black spot at the end of the cell of the primaries and a large white spot at the end of the cell of the secondaries. The other spots, which are always ringed about with white, are located much as in _L. icarioides_ (see Plate XXX, Fig. 29). Expanse, 1.15-1.20 inch. _Early Stages._--Unknown. _Fulla_ occurs in northern California, Oregon, Washington, and British Columbia. (6) =Lycæna icarioides=, Boisduval (=mintha=, Edwards), Plate XXX, Fig. 29, ♂, _under side_ (Boisduval's Blue).