SOUTH AFRICAN TERMITES. 63 



Radius : With three offsets, 2 ; with four, 4 ; with five, 3 ; 

 with six, 1. With three sectors, •"> ; with four, 1 ; with five, 5 ; 

 with six, 1. 



Calotermes d urban en sis Hav. 



The wiug venation of this species is much more variable 

 than that of any other species examined. 'I^hat the venation 

 also exhibits a wider range of extraordinary conditions has 

 no bearing on the matter of the variability of the venation. 

 A monograph would be requii^ed to deal with this subject, its 

 extent being limited only by the nuinber of wings available. 

 Although in many of the wings illustrated on Pis. VIII, IX, 

 the venation is abnormal, they serve vei-y well to illustrate 

 the features here discussed. 



The post-costa, independent on the fore wing only, is 

 regularly simple, but it merges into the costa anywhere 

 between one-quarter and one-sixth the length of the lamina. 



The sub-costa is generally simple, but occasionally it may 

 exhibit one outer branch. It unites with the costa at any 

 point fi"om one-half to three-quarters the length of the lamina. 



The radius possesses 4 to 8 offsets to the costa. These are 

 mostly simple and straight, but they may be variously sub- 

 divided or they may be imperfect, or they may anastomose 

 with one another. In 29 fore wings, counting subdivided 

 offsets as one, the average and common number was 7 ; in 

 28 hind wings the average and common number was 5 ; the 

 range was, however, the same for both fore and hind wings. 

 The irregularity of the subdivision of the offsets is illustrated 

 as follows : Of 47 wings, 24 possessed simple offsets, 13 had 

 one furcate offset, 9 had two such offsets, 1 had three and 1 

 four ; the remaining 8 had one offset with two branchlets. 



The media is usually simple; it may, however, be furcate 

 or well-branched. In the case of 62 wings (fore and hind) 

 21 had a simple media, 26 a media with a minor apical prong, 

 and 15 a media more or less well branched. 



The cubitus exhibits a variable number of offsets; these are 



