_Female._ Length 14 lines. Black, with shades of blue in certain lights; the abdomen with bright tints of blue and violet, caused by fine iridescent changeable pile; the legs have a similar pile, very bright on the femora within; the head and thorax with a short black velvety pubescence; the wings flavo-hyaline; the nervures pale ferruginous; the extreme base of the wings blackish, their apical margins with a narrow fuscous border. The legs spinose; the posterior tibiae with a double row of strong serrations. Gen. SPHEX, _Fabr._ 1. SPHEX ARGENTATA, _Dahlb. Hym. Eur._ i. 25. 1. _Hab._ Aru; Celebes; Sumatra; India; Greece; Africa; East Florida. 2. SPHEX SERICEA, _Fabr. Syst. Piez._ 211. 19. _Hab._ Aru; Malacca; Borneo; Java; Philippine Islands. 3. SPHEX AURIFRONS. _S._ niger; facie pube aurea vestita, alis flavo-hyalinis apice fuscis, abdomine pilis sericeo-aureis vestito. _Female._ Black; the face densely clothed with golden pubescence, the head having a number of scattered long golden-yellow hairs. Thorax thinly covered with long yellow pubescence, which is most dense at the sides of the metathorax; the tibiae, tarsi, and posterior femora ferruginous; the claw-joint of the tarsi black; the tibiae and tarsi with black spines; the wings fulvo-hyaline, their apex with a narrow fuscous border, the nervures ferruginous. Abdomen covered with a fine, thin, golden-reflecting pile; the apical margins of the segments rufo-testaceous, the testaceous margin produced in the middle into a triangular shape, most conspicuously so on the segments beneath. _Hab._ Aru. 4. SPHEX NITIDIVENTRIS. _S._ niger; abdomine nigro-caeruleo, laevigato, nitido; alis fuscis. _Female._ Length 12 lines. Black; the face with silvery pubescence, and thinly covered with long black hairs; the clypeus with a central longitudinal carina at the base, which terminates at the middle, from whence to the anterior margin is a broad, smooth, shining space. Thorax shining and finely punctured; the metathorax opake and covered with long, loose, black pubescence; the legs shining, the posterior tibiae with shining grey pile within; wings brown, darkest at their base. Abdomen blue, and very smooth and shining, oblong-ovate; the apical segment vertical. _Hab._ Aru. 5. SPHEX SEPICOLA. _S._ niger; facie pube aurea vestita; alis subhyalinis apice fuscis; abdomine nitido. _Female._ Length 9 lines. Black; the face densely clothed with golden pubescence, the cheeks with iridescent pile, with a long, loose, scattered pale yellow pubescence on the head and thorax; the mandibles smooth, shining black. The disk of the thorax with an obscure chalybeous tint, shining and finely punctured; the metathorax opake and finely rugose; the wings subhyaline, their apical margins fuscous, the nervures fusco-ferruginous. Abdomen with a slender subelongate petiole, and with a thin, silky, grey pile; the apical margins of the segments narrowly and obscurely rufo-piceous.