383 GERALD F. HILL. 



to the pointed apex. On the plains the nests are often very much larger and 

 frequently they have the long axis directed north and south or north-west by south- 

 east, the sides sloping to the bluntly wedge-shaped top, which is rounded off at each 

 end and never surmounted by numerous small points as in H. meridionalis, Frogg. 

 (Plate xi). Sometimes the western side is more or less convex and the eastern side 

 vertical or bent over, as in the latter species. The maximum size of such a termitarium 

 is about 6 ft. long by 2 ft. wide at the ground and 4 ft. high. Conical nests are not 

 uncommon. 



Only in recently constructed nests, built by large colonies whose former nests 

 have been dismantled, or smaller original nests of strong colonies, are the galleries 

 and passages within the termitarium numerous and extensive. In the great majority 

 of cases the structure is intensely hard and composed almost entirely of earthy 

 particles cemented together. The occupied portions are practically confined to the 

 top and sides, the internal galleries being gradually filled with rejectamenta until 

 they assume the toughness and density of the earthy portions. Additions are made 

 throughout the year, as in H. meridionalis, and not only after the rainy season has 

 set in, as stated by Jack (1897). These additions are small and local and usually 

 take the form of thin layers added to the sides (PI. xii, fig. 2), the insects working 

 from holes cut in the adjacent walls. The almost solid interior is pierced by a few 

 larger passages which pass down into the soil and beneath the walls. Food is stored 

 in the outer galleries and is generally mixed with the bodies of their dead. Near the 

 top of the nest the dead occupy more space than does the vegetable food. They 

 consist chiefly of nymphs of the winged forms in the stage when the wing rudiments 

 first appear ; but workers and soldiers are to be found also. In nearly all cases the 

 legs have been amputated. This habit of storing away the dead was first recorded 

 by Mjoberg (1920) in H. laurcnsis, Mjob., H. ^neridionalis , Frogg., and Eiitermes 

 tyriei, Mjob., in North Queensland, but has long been known to occur in H. 

 meridionalis in the Northern Territory, and in an allied species in Central Australia. 



Another type of termitarium is that in which there is a more or less solid 

 foundation a foot or more in height, upon which rest several larger or smaller cone- 

 shaped points (PI. xii, fig. 1). In many instances these nests are obviously constructed 

 on the sites of old nests ; in others there is nothing to indicate that such is the case. 

 An examination of the smaller nests, and especially those constructed on land free 

 from rock, shows clearly that the base rests on the natural surface, which is 

 penetrated only by a few passages. Such nests are easily pushed over intact, and if 

 not removed or broken into fragments, form the base of new termitaria, which the 

 insects soon construct in the characteristic cone-like form. Sometimes several of 

 these cones are built up vertically upon the upper surface of the now recumbent 

 old structure. 



The termitarium invariably contains two sterile castes, namely, soldiers and 

 workers. In all species of the genus Hamitermes {sensu restricto) the former caste 

 is represented by very few mature individuals, probably never more than 5 per cent, 

 of the total number of workers, and in this species probabty less than | per cent. 

 When the nest is broken into there is a general retreat to the remaining galleries, 

 neither caste making any attempt to defend themselves, their fellows, or their home. 

 In all strong colonies there are present also great numbers of 3-oung forms in various 

 stages of development. Reproductive forms, or forms which mature into them, are 

 nearly always present. In the earlier stages preceding sexual maturity the latter 

 are creamy white or white, soft-bodied insects, longer and more slender than the 

 workers and possessing short wing-rudiments or wing-buds.* These nymphs are 

 often present in great numbers and appear to be destroyed and stored for food when 



* The term "nymph" is used in this paper to denote the j'oung of reproductive forms in 

 which the wing rudiments are evident. The word "larva" is used to denote all apparently 

 undifferentiated young. 



