22 Proceedings of the Royal Irish Academy. 



much shorter and markedly thickened a little beyond the base (fig. 122). 

 Naturally the first conclusion drawn was tliat the latter must belong to a 

 distinct species, but when a third insect from Silhouette was seen to liave 

 one long and sleudei", and one short and thick feeler, and a fourth to have the 

 basal half of its feeler thick, and the distal half slender (the junction between 

 the two sections is showu in fig. VIZ), it was clear that these appendages must 

 be capable of great modification in appearance. This was confirmed when 

 one of the short and thick-feelered insects was transferred from alcohol to 

 caustic potash with the result that the distal half of the feeler lengthened 

 out, resuming its previous contracted condition when the specimen was passed 

 on into glycerine. Study of well-cleared specimens show that each segment 

 of the feeler consists of a cup-shaped middle region broadening distally, 

 covered with firm cuticle, while the proximal and terminal regions are covered 

 with thin flexible cuticle, which has a wrinkled surface in partly contracted 

 specimens. "What happens on contraction is that these firm, cup-shaped 

 regions are pulled back into each other, the flexilile intermediate tracts being 

 invaginated (fig. 123). For this purpose the feeler is provided with two 

 strands of longitudinal muscle. Xo reference to this interesting change of 



O Co 



appearance seems to have been made hitherto, and it will be necessary for 

 systematists to consider it in future when describing the feelers of insects 

 of this family. 



The jaws of the South European lapyx have lieen well described by 

 Meinert ('65), von Stummer-Traunfels ('91), and Borner ('08), and as those of 

 the Seychelles species resemble these very closely, it is needless to dwell upon 

 them, though considerable difference of opinion has been expressed as to the 

 homology of the structures usually regarded as maxillary. The under 

 surface of the head of /. sUrcstris (fig. 125) shows the features usual in the 

 labium of this family, with the stumpy, bristly, unjointed palps [p) that 

 characterize the typical genus lapyx. 



Very little attention seems to have been paid to the genital armature in 

 lapyx. Grassi ('88, pp. 569, 572, pi. iv, fig. 47, pi. v, fig. 52) described and 

 figured somewhat diagrammatically the external reproductive organs in both 

 sexes, and Verhoeti' drew the male ('0-4, pi. v, fig. 22) and female ('03, pi. xviii, 

 fig. 8a) structures of Heterowpyx navae-zeelandiae. 



In both sexes there is a small sub-semicircular chitinous plate connected 

 by flexible cuticle with the hind edge of the eighth abdominal sternum, behind 

 which it is usually reflected. When protruded, therefore, it appeai-s between 

 the eighth and ninth sterna. In the male (figs. 132, 133) this plate has a 

 marginal row of long bristles, and its ventral edge is beset thickly with short 

 spines. \'entral to this plate extends a straight, haii-y ridge (fig. 132 /•), from 



