78 CLAUDE FULLER. 



The foregoing interpretation is based upon an examination 

 of the tracheae of the wing-sac. Some young nymphs, with 

 eight or nine months of development still before them, ex- 

 hibite(1 peculiar and somewhat erratic buds of wing tracheae, 

 and figs. 160 to 163 illustrate the conditions found in one of 

 them. Fig. 160 shows the post-costa, radial, and furcate 

 cubital; also a vestigial sub-costal on the radial. Fig. 161, 

 although belonging to the mesonotum, is very different; here 

 a similar post-costal is set much nearer a radial that wants the 

 vestigial sub-costal, and against the stem of the furcate cubital 

 springs a strong bud which may be considered as that of the 

 medial. Fig. 162 is a condition analogous to that shown in 

 fig. 161 ; the post-costal is, however, well removed from the 

 radial and a medial springs from the stock of the cubital. 

 Fig. 163 represents a fourth and very different condition ; 

 here the post-costal is as in the other wing-sacs, whilst, 

 apparently, the radial and medial both spring from the stock 

 of the cubital. Just what the subsequent development might 

 be it is impossible to say, but in twenty-three out of twenty- 

 four wing-sacs from six older nymphs, wanting a month or 

 two for maturity, the condition of the trachea? was as shown 

 in fig. 164, except that in some the furcation of the cubital 

 was much deeper-seated, so that the stock appeared to be 

 double-barrelled. The tracheae in the wing-sacs of these older 

 nymphs probably had not reached their full development. 

 It is to be noticed that the post-costal is fairly short and 

 that the radial has similar branches to the radial of Hodo- 

 termes, Calotermes, and C r y p t o t e r m e s ; these branches 

 need not, however, be regarded as the predecessors of the 

 struts connecting the radius and costa in the final wing. 



The one wing-sac that was unusual presented an extra 

 trachea, fig. 165 (PI. X), which may be regarded as the 

 medial. An examination of the basal connections showed 

 that this extra trachea arose from the cubital stem, fig. 166, 

 a condition that might well be expected from the juvenile 

 conditions already described. 



I have found no final wing with an extra rib, but, curiously 



