478 HABITATIONS OF INSECTS. 



ramid, truncated at one-third of its height 8 , and Sted- 

 man, when in Surinam, once passed ant-hills six feet 

 high, and at least one hundred feet in circumference b . 



The nest of Formica brunnea is composed wholly of 

 earth, and consists of a great number of stories, some- 

 times not fewer than forty, twenty below the level of the 

 soil, and as many above, which last, following the slope 

 of the ant-hill, are concentric. Each story, separately 

 examined, exhibits cavities in the shape of saloons, nar- 

 rower apartments, and long galleries which preserve the 

 communication between both. The arched roofs of the 

 most spacious rooms are supported by very thin walls, 

 or occasionally by small pillars and true buttresses; some 

 having only one entrance from above, others a second 

 communicating with the lower story. The main galle- 

 ries, of which in some places several meet in one large 

 saloon, communicate with other subterranean passages, 

 which are often carried to the distance of several feet 

 from the hill. These insects work chiefly after sunset. 

 In building their nest they employ soft clay only, scraped 

 from its bottom when sufficiently moistened by a shower, 

 which, far from injuring, consolidates and strengthens 

 their architecture. Different labourers convey small 

 masses of this ductile material between their mandibles, 

 and with the same instruments they spread and mould 

 it to their will, the antennae accompanying every move- 

 ment. They render all firm by pressing the surface 

 lightly with their fore feet ; and however numerous the 

 masses of clay composing these walls, and though con- 



* Huber, Recherches sur les Mceurs des Fourmis, p. 168. 

 b Stedman's Surinam, i. 169. 



