crtheless, had I examined no other Stylopid than Elciiclius, I 

 might possibly have agreed with his interpretation of the mouth 

 parts, but the examination of a species of a genus alhed to 

 Xciios, and more especiahy a close s.udy of the head of a sjiecies 

 cf the subgenus Bnicsia (hereafter described) and of a species 

 of Halictophagiis, leads me to favor a different interpretation. 

 The delicate transverse band on the under side of the head T 

 agree in considering labium, the two-jointed organ on either 

 side of it being probably the labial palpi. The part called ligula 

 by Eaton requires close study being- in many Stylopidae bent at 

 an angle, to form two planes; when t'he upper part is seen in 

 full surface view, the lower part meeting it at a strong angle 

 slopes very strongly backwards from the point of meet- 

 ing. This structure might be called an epistome, but it is pos- 

 sible that the lower part is really the labrum or upoer lip, the 

 position of which it occupies. Between the apex of the lip and 

 the labium approximated to it, is the closed, or obsolescent oral 

 aperture. The so-called mandibles are probablv rightly so 

 called. Adopting Eaton's interpretation the oral aperture of 

 Elenchus is bounded by and in fact leads into the frontal pro- 

 cess, but this seems to me certainly erroneous. According to 

 the view here suggested by me, the mouth parts of the Stylo- 

 pidae are not so extremelv remarkable. The difBcultv of study- 

 ing the insect is not only due to the small size and delicate 

 structure, but also to the fact that the sides of the face within 

 the eyes have sharp orotuberant edges, so that this part is more 

 or less deeply excavated, the other structures being partly or 

 wholly inmiersed, and further obscured by the mandibles and 

 palpi. In Bnicsia aiistralciisis however, and HalictopJiagus 

 sclnvarzii, the face is much more open, and after dissecting off 

 the mandibles and palpi the parts can be studied with compara- 

 tive ease. It was therefore found advisable to carefully examine 

 these before coming to any decision as to the mouth-parts of 

 Elenchus. In PI. I, fig. i, is a diagrammatic view of the front 

 of the head, simplified from what is actually seen in Bnicsia and 

 Halictopliagiis, as I interpret it, actual figures of these being 

 given on the same plate, fi,g. 2 and 5. The parts indicated by 

 the letters b and d together represent what I have already 

 called eoistome, of which however, the lower portion (d) may 

 be labral; e is the labium, and the closed, or at least obsolescent, 

 oral opening is the slit between d and e. For the rest, the other 

 parts are sufficiently explained in the description of the figures, 

 but special attention must be called to the foramen (c) at or 

 rear the junction of b and d. This exists in Elenchus, Halic- 



