162 SMITH ON HTMENOPTEBA OE ARU ISLANDS. 



Female. Length 8^ lines. Black, smooth, and shining ; the head and 

 thorax very delicately punctured ; the face and clypeus below the in- 

 sertion of the antennae densely covered with silvery-white pubescence ; 

 the anterior margin of the clypeus rounded and much produced, with 

 a slight curving upwards at its margin ; the mandibles yellow, with 

 their apex ferruginous ; the palpi pale testaceous ; the inner orbits of 

 the eyes very deeply notched. Thorax : the metathorax, the sides, 

 and beneath with a thin silvery-white pubescence, most dense on the 

 former ; the metathorax not distinctly enclosed at its base, but with 

 two shallow impressed lines, which mark the form of the usual en- 

 closed space ; a central longitudinal channel extends from its base 

 to the apex, slightly sub-interrupted in the middle ; the wings hyaline 

 and iridescent, the nervures dark fuscous ; the anterior and inter- 

 mediate tibiae in front, their tarsi, the apical joints of the posterior 

 pair, and the base of the tibiae very pale ferruginous ; the claw-joint 

 of the intermediate and posterior tarsi fuscous above; the calcaria 

 pale testaceous. Abdomen, the second, third, and base of the fourth 

 segment more or less ferruginous ; the apex of the basal petiolated 

 joint ferruginous beneath. 



Hah. Aru and Key Island. 



(j^en. Crabro, Fah\ 



1. Crabro solitarius. C. niger; abdomine petiolato ; scapo flagel- 

 lique articulo ultimo, collari, tuberculis, postscutelli maculis duabus 

 flavis ; pedibus petioloque basi ferrugineis. 



Female. Length 5 lines. Black and opake ; the head large, quadrate, 

 and wider than the thorax ; the ocelli in a curve on the vertex ; the 

 clypeus covered with silvery pubescence, carinated in the middle, and 

 slightly produced ; the scape and basal joint of the flagellum pale 

 yellow. Thorax : an interrupted line on the collar, the tubercles, a 

 spot beneath the wings, and two minute ones on the postscutellum 

 yellow ; the disk of the thorax longitudinally delicately rugose ; the 

 metathorax obliquely striated, with an enclosed space at its base, and 

 having a central longitudinal channel, the sides covered with thin 

 silvery pubescence ; the wings hyaline and iridescent, the nervures 

 fuscous ; the legs ferruginous, variegated with yellow. Abdomen : 

 the basal petiolated segment ferruginous, with its apical half black 

 above ; the apical segment with an angular shape at its base, which 

 is smooth and shining, with its lateral margins carinate, the extreme 

 apex ferruginous; beneath smooth and shining, with the apical 

 margins rufo-piceous. 



Hah. Aru. 



This species would, according to the views of some Hymenopterists, 



belong to the genus Rhopalum of Kirby. 



