_Male._ Length 7-1/4 lines. Head yellow, above the insertion of the antennae black; antennae black, with the scape, basal joint of the antennae, and the mandibles ferruginous; the flagellum obscurely ferruginous beneath; the clypeus produced at the apex into an acute tooth. Thorax pale ferruginous; the metathorax black, with a ferruginous spot on each side in front; the scutellum with a reddish-brown spot in the middle, the postscutellum yellow and subinterrupted in the middle; the sides of the thorax yellow anteriorly, the yellow portion with two black spots; the legs slightly variegated with yellow; wings subhyaline and brilliantly iridescent, the marginal cell with a fuscous cloud. Abdomen brown; the petiole pale testaceous at its apex and ferruginous beneath, longer than the head and thorax; the second segment has a yellow macula on each side, and, beneath, a smaller spot on each side in a line with the side spots; the first segment has its basal portion yellow beneath, and a blackish spot in the centre rather behind the middle. _Hab._ Aru. This species in many particulars agrees with the _I. nitidipennis_ of Saussure, but differs in too many, I think, to be considered the same species; the second recurrent nervure is straight at the upper extremity, then curved towards the margin of the wing, and again straight at its lower extremity; the third submarginal cell is much wider than the fourth. Gen. ICARIA, _Sauss._ 1. Icaria maculiventris, _Sauss. Mon. Guepes Soc._ p. 23. 1.--Rhopalidia maculiventris, _Guer. Voy. Coq. Zool._ ii. pt. 2. _Ins_. p. 267, pl. 9. fig. 8. _Hab._ Aru; New Guinea. 2. ICARIA NIGRA. _I._ nigra; clypeo antice angulato; metathorace concavo et transversim striato; alis hyalinis. _Female._ Length 6 lines. Black, punctured and opake; the clypeus terminating in a sharp-pointed angle; the base and apex of the mandibles rufo-piceous; the scape ferruginous in front; the face with a thin, fine, griseous pubescence. Thorax slightly margined in front; an obscure testaceous spot on each side of the postscutellum, the metathorax concave and transversely striated; wings hyaline. Abdomen with a short petiole to the basal segment, which is very short and campanulate; at its posterior margin are two minute, obscure, pale spots; beneath, the margins of the apical segments are rufo-piceous. _Hab._ Aru. 3. ICARIA FASCIATA. _I._ nigra; clypei margine antico, maculis duabus postscutelli flavis; segmentis abdominis ad apicem flavo anguste fasciatis.