SOUTH AFRICAN TERMITES. 61 



exhibits, in detail, a reticulation that the pre-existing trachea- 

 tion has given rise to, but as the wings harden this completely, 

 or almost completely, disappears; the degree differs apparently 

 in diiferent races. 'i'he same factor also obliterates that 

 portion of the marginal which extends along the inner edge. 



It may be said literally that the final wing mirrors the 

 main trachea3 of the wing-sac with remarkfible precision, 

 and, with minor exceptions, it is a fact that the ribs represent 

 the tracheal arrangement. Fused ribs arise from the amal^a- 

 mation of thickenings. It has been shown that anastomosis 

 may occur within the body of Cryptotermes between 

 tracheae, which touch one another, but nothing of this sort has 

 been found in the wing-sac. Tracheae may apply them- 

 selves closely to one another, or they may cross one another 

 in the wing-sac, but they do not anastomose. 



Independent ribs are to be sought for between the offsets 

 of the cubitus. In the Metatermitidas they are usually 

 offsets that have lost their basal connections. In Crypto- 

 termes they succeed thickenings forming about the in- 

 growing tips of cubital offsets, figs. 142 (PI. IX), 146, 149 

 and 152 (PI. X). 



The following details regarding the variation of the 

 venation as a matter apart from the presence of extra ribs 

 and other extraordinary conditions, are given in a condensed 

 form. The subject is one that can be considerably elaborated 

 but to do so would serve no useful purpose. In all instances 

 the results given are based on the examination of the wings 

 of the insects of one nest in one season. 



Hodotermes viator [Latreille] . 



The post-costa is simple, as a rule, but it may exhibit one 

 or two minute offsets to the costa, more particularly in the 

 fore wing. 



The sub-costa may also have one or two outer branches ; 

 in rare instances there are more than two, and then well- 

 developed. 



