SOUTH APKICAN TERMITES. 83 



present in wing-sacs, it is remarkable that more evidence 

 of it is not to be found in final wings. It is possible, however, 

 that the thickening forming about it coalesces with that 

 forming about the pseudo-medial, and any branches it may 

 produce appear in the final wing as branches of the pseudo- 

 media. 



From an examination of a considerable number of nymphs 

 in various stages of growth, it is possible to say that ordi- 

 narily the trachete of the wing-sac arise from two buds, the 

 radial and the cubital, of which the latter is the first to 

 develop; compare figs. 195, 196 with fig. 197. In a later 

 stage the three principals are found as in fig. 198. Still later, 

 developments comprise, ordinarily, the branching of the cubital 

 and the appearance of a sub-costal. Extraordinarily, a post- 

 costal or an anal, or both, may appear, fig. 199, and either of 

 these two trachea3 may lie extended into the wing-sac or may 

 bend back into the thoracic cavity. 



Quite frequently the wing-sac is penetrated by a principal 

 trachea, extra to the normal quota ; this is the medial, fig. 200. 

 In all cases except one, in which such a medial was found, 

 the cubital was duplicated. In the one exception the cubital 

 Avas single, but the medial was duplicated. 



Concerning the wings reproduced it may be said that 

 figs. 188, 189 represent companion fore and hind wings, both 

 of which may be considered as normal, but the condition of 

 the hind Aving, fig. 189, gives rise to the suspicion that the 

 venation is due to a true media as well as a pseudo-media and 

 cubitus. Fig. 190 represents a normal wing; the only one 

 noticed in which the radius possessed a true inner branch or 

 sector. Fig. 191 is awing in which the media is undoubtedly 

 fully developed, and in the two wings, figs. 192, 193, I think 

 the rib Avhich unites with the radius arises from a true medial 

 trachea. Fig. 194 represents a quite abnormal condition due 

 to the pseudo-medial trachea applying itself in part to the 

 radial. 



6* 



