OBSERVATIONS ON SOMK SOUTH AFRICAN TERMITES. 403 



4000 to 4900 ft.), it is incredibly abundant; so much is it so 

 that one may travel by train for a whole day through country 

 so thickly studded over with mounds as to look as if overrun 

 by ii multitude of grazing- sheep. This extreme abundance 

 on this wide plain, hot in summer and bleak in winter, 

 indicates that the species flourishes best in a dry atmosphere. 

 Here the denudation of grazing land caused by the presence 

 of these numerous colonies, proceeding year by year, must 

 impoverish the land, but the species woi'ks in so insidious 

 a manner that it is extremely doubtful whether those most 

 affected — the stock owners — have the slightest idea of the 

 loss entailed. 



The nest of trinervius is a "hive-nest" assuming the 

 form of a globular mass, the lower quarter of which is 

 embedded in the soil. In Natal the mounds are symmetrical 

 half-spheres, whilst the base inset in the soil is a low 

 in\erted cone. Regularly rounded domed mounds may also 

 be found in parts of the Transvaal and Orange Free State 

 Avhere moister conditions obtain, and this is the prevailing- 

 shape in the southern region of Cape Colony. Where 

 conditions are drier and the summer rains come in fierce 

 tropical showers, regular contours are uncommon, and the 

 mounds are roughly shouldered and tend to become conical. 

 This alteration of the contour is due to spasmodic additions 

 to the nest, coupled with weathering ; the colonies under 

 these conditions adding humps to the nest and not making a 

 crust which envelopes at least two-thirds of the surface, as 

 they do under milder and more uniform climatic conditions. 

 Along the high ridge (5000 ft.) of the Witwatersrand 

 (Heidelberg to Germiston) about half the mounds have a 

 somewhat bizai-re appearance (PI. XXIX, fig. 17), and on 

 the summit of some of these small or quite large tapering- 

 cones are developed. There seems to be nothing to account 

 for this local eccentricity. It may be said of this species 

 that it does not make bricks without straw, as a considerable 

 amount of grass is always incorporated into any new addition, 

 of the nest. 



