swollen on its inner side. The third segment is slightly longer and less bulbous, while the last two segments are slender and about the same length as the first segment. Sensory hairs and setae are present on the distal portion of the first segment, and occur densely over the entire surface of the other segments. The galea (ga.) is flattened and spathulate. Around its outer edge are setal sensilla, while over its inner edge and part of the surface, are very fine hairs. The lacinia (lc.) is much smaller, and fits into the curved base of the galea. It is entirely covered with fine hairs. The labial assemblage is comparatively small, the entire length of the prementum including the ligula being only slightly greater than that of the stipes. The submentum (smt.) is membranous, and carries no sensory hairs. The prementum (prmt.) is pyriform, heavily chitinised, and supplied with scattered sensory hairs and placoid sensilla. It is very strongly inflexed at the margins. At its distal end the glossae (gl.) and paraglossae (pgl.) articulate, and just below these, the labial palps (lb. plp.) arise from definite palpigers (plg.). These palps are four-jointed structures with a similar supply of sensilla to those present on the maxillary palps. In the labial palps, the middle two segments are squat and pyriform. The glossa is a large flat bilobed structure with numerous parallel grooves and ridges in its surface. It contains several types of sensilla, including the symmetrically placed, almost straight chaetae projecting anteriorly, and an anterior row of basiconic sensilla. The apical margin is in the form of a comb, with straight, close bristles all of uniform length. Paraglossae occur basally at each side of the glossa, and these pad-like structures are covered dorsally with short, stout, curved sensilla. The papillate hypopharynx at the base of the glossa marks the opening of the salivery duct. Alimentary System (Plates 17 and 18). The mouth opens into the pharynx (ph.) which lies vertically above it. The pharynx (Fig. 10) is lined with thick chitin and is shaped more or less like a D lying with its flat side ventral. The floor of the pharynx is in the form of a chitinous plate slightly raised in the middle. The lateral angles are much folded, and very flexible, allowing the roof and floor to be pressed together by muscular contraction. Strong muscles are inserted in this chitinous lining both dorsally and ventrally. Dorsally these muscles are mainly longitudinal, while ventrally there are strong transverse bands. The epithelium of the fore-gut is homologous with the hypodermis, and in the vicinity of the pharynx is fairly typical of it. In the oesophagus proper (oe.) which extends from the pharynx back to the posterior end of the petiole, the layers take on a more typical arrangement (Fig. 11). The cuticle is very thin, and raised to form innumerable small lobules and papillae. These contain prolongations of the underlying epithelium, the cells of which are more or less cubical. These cells have medium-sized nuclei, and do not appear to be markedly glandular or secretory in function. Outside this epithelium is a basement membrane, and outside this again are scattered longitudinal muscle fibres overlain by circular fibres, both bearing fine striations.