46 CLAUDE FULLER. 



Vf. The Calotermite Stem. 

 Plate IV, figs. 21a, b, c. 



The respiratory system possessed by the young of Oalo- 

 termes and Cryptotermes on leaving the egg is more 

 ample and more complex than is the Metatermite form. 

 Moreover, it becomes moi'e complex as growth proceeds. 

 Apart from this, various structural features — especially the 

 sculpture of the head and the compression of the thorax 

 — alter the courses of the trachete, produce unusual post- 

 embryonic developments, and make its detailed examination 

 more difficult. 



For the purpose of this section it will be sufficient to 

 compare briefly the system of Cryptotermes with that of 

 Termes natalensis. The first difference to be noted is the 

 presence of an extra pair of longitudinal tracheae which lie 

 along the floor of abdomen and thorax, fig. 21a (PI. IV). 

 These may be said to be composed of a series of loops linking 

 up the ventral commissure, and extend from the commissure 

 of the first to that of the tenth pair of spiracles, continuing 

 beyond the last in a tail-like form into the ventral caudal 

 region, and so resembling the tails of the dorsal longitmlinal 

 trunks. This extra pair of tracheae is also exhibited by 

 Calotermes durbanensis, Hodotermes spp., and by 

 Rhinotermes putorius. 



In slightly more mature nymphs of Cryptotermes there 

 is a striking X-shaped trachea across the floor of the pro- 

 thorax (fig. 21a). This arises out of the brief anastomosis of 

 the median point of the cervical with that of the ventral 

 commissure of the first spiracles. The two tracheae are 

 approximated at birth and joined by a short isthmus ; they 

 gradually fuse, and later are stretched taut so as to form 

 a regular X- ^ similar trachea has been observed in Calo- 

 termes, but it, appears to originate differently, and has not 

 been satisfactorily studied. 



