SOUTH AFRICAN TERMITES. 35 



ineso- and iiietatliorax. They are Y-shaped, and the stem of 

 the Y has arisen by the coalescence of the two tracheae 

 forming the arms. Further evidence of this is found in the 

 temporally separation of the two {x.x.) within the tibia. 



The six pairs of visceral trachese take an inward and then 

 cephalic course, and as each pair traverses the whole of two 

 sections the anterior pair enter the region of the meta- 

 thorax, x.x., fig". 10. 



On the dorsal longitudinals, paired hndsx.x.x.x., etc., fig. 11, 

 occur almost regularly upon each section or ai'ch and later 

 develop into arborescent trachea?, fig. 12, which extend trans- 

 versely under the dome of the dorsum, towards the median 

 region. 



Upon the first, third, and fifth to tenth commissures there 

 are two buds, on the second there are four, and on the fourth 

 there are none, fig. 13. 



Vb. The Cephalic and Prothoeacic System. 



Plate III, figs. 14-19. 



The stem within the head, neck, and prothorax lies before 

 the first pair of spiracles, and these aerify it, figs. 18 and 19 

 (PI. III). Its most conspicuous feature is a great U-shaped 

 trachea which projects through the prothorax, neck, and 

 occipital foramen, and lies close to the floor of the head, 

 fig. 14. This is an anastomosis of the cephalic terminals of 

 the two spiracular trunks, but may owe its origin to the 

 linking up of the terminals by a transverse commissure. 

 From the dorsal surface of each stem of the U just anterior 

 to the spiracles and within the prothorax, arises a large dorsal 

 trachea (marked x. in figs. 14 and 15). Each dorsal accom- 

 panies its corresponding stem of the U-shaped trachea 

 through the neck and foramen, each then ascends into the 

 dome of the head, and, extending forwards, terminates 

 {y., fig. 15) in the tip of an antenna. Each is again con- 

 nected, or braced, within the head, to the U-shaped trachea 

 by a vertical commissure (fig. 15, z.z.). These two upper 



3* 



