452 CYllTID.4: 



cell which lies above the discal cell is a second portion of the upper basal cell, and 

 not a basal portion of the first posterior cell ; the second basal cell is long and 

 narrow. A comparison of this venation with that of the Nemestrinidce {Ilermoneura, 

 fig. 251) shows every one of the same veins and veinlets, except the strong discal 

 cross-vein close to the base of the discal cell which is quite absent in Ilermoveiira. 

 It would appear that an absolutely different principle has been adopted (in two allied 

 groups) to strengthen the wings ; in the Nemestrinidce by tying the elongated end 

 veins together (exaggerated to an extraordinary degree in Nemestrina, fig. 250), but 

 in the Gyrtidce by connecting the anterior and posterior parts of the wing by a 

 strong tie near the base and also (in Lasia, etc.) by a second tie towards the end of 

 the wing, but subsequently when the Cyrtidce developed the floating balloon-like 

 flight this second tie was allowed to die out and tlie outer veins to become obsolete. 

 The course of the " diagonal " vein in the NemestrinidcB is in no way repeated in 

 the Cyrtidce (even though a straight diagonal vein composed of entirely difi"erent 

 veins exists in Lasia, etc.), but that is because the whole of the outer and posterior 

 veins in the Nemestrinidcfi slope upwards towards the wing-tip, while in Lasia 

 only the cubital fork curves upwards. 



The venation of Eidonchits (fig. 259 B) shows but little change from I^asia, except 

 that the cubital fork is less Hernioneura-YikQ and is distinctly removed from the 

 supernumerary cross-vein. In Pteroj^exus (fig. 259 C) the venation is again almost 

 the same, but the clue is given to the venation of Pterodontia (fig. 260 B and C). In 

 Holops (fig. 259 F) and Cyrtus (fig. 259 G and H) the same type of venation can 

 easily be traced, though some veins become obsolete before reaching the wingmargin, 

 but in Cyrtus the upright nature of the upper branch of the postical vein becomes 

 instructive as to future developments. Megalyhus (figs. 259 I) and E) exhibits an 

 important change, but the second upper basal cell and the three veinlets from the 

 discal cell still remain ; the fork of the cubital vein has disappeared, and in fig. 259 D 

 the third veinlet from the discal cell (and with it the closed fourth posterior cell) 

 has apparently gone, but fig. 259 E would seem to show that this third veinlet does 

 still exist and that it is the outward continuation of the postical vein which had 

 disappeared* (this again may give a clue to the venation of Oncodes and Acrocera), 

 the lower branch of the postical vein bends down into the anal vein more abruptly 

 than in any other genus of the Cyrtidte. In Astomella (fig. 260 A) a somewhat 

 intermediate stage occurs in which one can now trace an unforked cubital vein, 

 because the apparent lower branch has been accounted for in the previous genera ; 

 the closed fourth posterior cell (in this genus actually the third though apparently 

 the fourth) remains, as well as a small cross-vein and a fully developed postical fork, 

 but the second veinlet from the discal cell has entirely disappeared, and consequently 

 the posterior cells are reduced in number ; one difficult point becomes cleared up in 

 this genus, as it becomes practically cei'tain that the wide open space at the wing-tip 

 is the first posterior cell and not a submarginal cell. The next stage comes in 

 Pterodontia and shows a great change in the development of the discal vein ; judging 

 from Pterojyexus (fig. 259 C) there can be no doubt about the radial vein which 

 curves up into the enlargement of the costa, and then an examination of the wing of 

 P. analis (fig. 260 B) shows the continued presence of the two discal cross-veins, and 

 at the same time shows that the so-called outer upper basal cell has become merged 

 into the discal cell, i.e. the upper branch of the discal vein has disappeared but the 

 upper veinlet from the discal cell remains ; the lower branch of the discal vein 

 bends sharply downwards and (judging by Megalyhus) receives the short upper 

 branch of the postical vein, and then continues onwards to the wingmargin ; in my 

 opinion all this lower margin of the discal cell and the veinlet thence to the wing- 

 margin belong to the discal vein and are not in any way a continuation of the upper 

 branch of tJie postical vein ; in P. Virmondii (tig. 260 0) tlie outer discal cross-vein 

 and the upper veinlet from the discal cell disajipear, and apparently there is no 

 upper brancli to tlie postical vein, or if thei'e be one it is anastomosed for a short 

 distance with tlie lower branch of the discal vein; in P. analis there are three 

 posterior cells, but in P. Virmondii only two. From Pterodontia one jjasses on to 

 Oneodes (fig. 260 D) because the discal cross-vein can still be traced (even though 

 faint) ; the upper basal cell is much longer, so that the discal cross-vein is further 

 from the base of the wing, and consequently tlie supernumerary discal cross-vein is 

 no longer required and has disappeared ; the shape of the anal cell (in 0. pallipes) 

 seems to indicate that Oncodes may be a degraded form of Astomella, a form m which 



* This character is not constant in Megalijhus tristis. 



