Notwithstanding the numerous groups which have been recently withdrawn from this genus, it still includes a great variety of modifications of form which would amply justify further subdivision. Even the few examples which have been selected for illustration might afford the types of more than one group; but, for the reasons already mentioned, we prefer presenting them according to Latreille’s arrangement. Most of these insects are beneath the middle size, they are usually adorned with very beautiful colours on the surface, and ornamented with ocelliform spots beneath, a circumstance which has suggested the name. They are distinguished from the immediately preceding genera by having the palpi of ordinary length, or rather short, and all the legs complete, or adapted for walking, in both sexes. The group to which the first species represented belongs, has the costa of the upper wings more or less arched, particularly towards the base, and the hinder margin of the same wings is very slightly concave, especially in the male. The hinder wings have two linear narrow tails towards the anal angle. _P. Marsyas_ is a native of Brazil, Guiana, and some other countries of South America. It is greenish-blue on the upper side, changing with the direction of the incident light into violet, the costa and apical angle of the upper wings widely black. Beneath the colour is lilac, glossy, with seven or eight small black spots, surrounded by a white circle, scattered over the disk of each wing; the anal angle bluish-green, with two short white transverse streaks and two pretty large black spots; tails black with the extremity white, the outer one about half the length of the other. Body blue above and whitish beneath. The antennæ, as in most of the Polyommati, are black with pale rings. [Illustration: PLATE 26. _1. 2. Polyommatus Marsyas._ _3. 4. ---- Endymion._ 1 & 2 from S. America. 3 & 4. Surinam. _Lizars sc._] POLYOMMATUS ENDYMION. PLATE XXVI. Figs. 3, 4, _Fem._ Pap. P. R. Endymion, _Fabr. Herbst. Pap._ Pl. 298, fig. 1, 2. Pap. regalis, _Cramer_, Pl. 72. fig. E, F. (Fem).