158 BIOLOGY OF NORTH AUSTRALIAN TERMITES, 



postclypeus large, about twice as wide as long, semicircular behind, truncate in 

 front, setaceous. Eyes small (.208 x .272), projecting very little, separated from 

 the lower margin of the head by a space equal to about half their short diameter. 

 Ocelli small, oval, separated from the eyes by a distance equal to that separating 

 the eye from the lower margin of head. Fontanelle large, elongate oval. An- 

 tennae (Text-figs. 37-39) 15- or 16-jointed, variable in segmentation, sometimes 

 differing markedly in the same individual, the fii-st always short and stout, second 

 always very short and narrow, sometimes shortest of all, third generally shortest 

 and narrowest but often equal to second and fourth. 



Thorax (Text-fig. 40) : Pronotum small, narrower than head, straight in 

 front, with an oblique, elongate depression on either side near the median line 

 and a smaller one in each antero-lateral area, sides rounded to the emarginate 

 posterior margin, densely setaceous. Meso- and metanotum with posterior margin 

 markedly sinuate. 



Legs short, moderately stout and setaceous; tibial spurs 3:2:2. 



Wings: Wing-stumps clothed with long and short setae, suture straight. 

 Wings long and narrow, veins distinct to the wing-margin, margin very setaceous ; 

 membrane setaceous and densely sculptured. Venation slightly variable but 

 generally as shown in Plate xxv., fig. 1. Rudiment of subcosta visible beyond 

 cross suture. 



Abdomen widest in the middle, rounded at the apex, densely clothed with 

 long and short pale setae; cerci very small. 



Measurements : 



Length: with wings 12.5 — 13.0 mm.; without wings 6.5 — 7.0. 



Head: long 1.50; wide 1.08; deep 0.47. 



Antennae (15- 16-jointed) 1.88. 



Pronotum: long .61; wide .98. 



Wings: fore, long 10.00, wide 2.03; hind, long 9.50, wide 2.77. 



Tibia iii, long 1.17. 



Abdomen, wide 1.41. 



Identification. — ^The identification of the alate form described above is based 

 on the comparison of soldiers and workers associated with them, with the types 

 of these castes (from the same locality). 



Biology. 



On the 17th and 20th November, 1914, immense numbers of alate termites 

 were seen to rise from the ground during and just after a. driving rainstorm, 

 which swept over the town about 2.30 p.m. The "swarm" was found to be is- 

 suing from many small, circular openings in the surface of the soil over an area 

 of about 20 feet in diameter. Soldiers and workers poured out with the winged 

 forms and, like them, soon became a prey to ants and lizards, which had ap- 

 peared with their customary promptness. The exit holes were guarded by other 

 soldiers and workers as long as "swarming" lasted, after which the latter closed 

 the openings with cement-like material, leaving many of their fellows to perish 

 in their struggles with their enemies. Examples of all castes were collected at 

 the exit holes only to obviate the possibility of confusing them with another 

 species (H. darwini, n.sp.) which was known to infest the same allotment. An 

 attempt was made to follow the underground tunnels back to their nest, but this 

 was found impracticable. This species, like H. germanus Hill and H. darwini, 

 n.sp., appears to feed exclusively on decaying vegetable matter. None of them, 

 as far as known, build termitaria. 



Locality. — ^Northern Territory: Darwin (G. F. Hill). 



