HABITATIONS OF INSECTS. 483 



sons. When they wish to heighten their habitations, 

 they begin by cov^ering the top with a tliick layer of 

 clay which they transport from the interior. In this 

 layer they trace out the plan of the new story, first 

 hollowing oat little cavities of almost equal depth at 

 different distances from each other, and of a size 

 adapted to their purposes. The elevations of earth 

 left between them serve for bases to the interior walls, 

 which, when they have removed all the loose earth 

 from the floors of the apartments, and reduced the 

 foundations to a due thickness, they heighten, and 

 lastly cover all in. M. Huber saw a single working 

 ant make and cover in a gallery which was two or three 

 inches long, and of which the interior was rendered 

 perfectly concave, without assistance ''. 



The societies o£ F.fuligmosa,ljatr. make their habi- 

 tations in the trunks of old oaks or willow-trees, gnaw- 

 ing the wood into numberless stories more or less hori- 

 zontal, the ceilings and floors of which ai'e about five 

 or six lines asunder, black, and as thin as card, some- 

 times supported by vertical partitions, forming an in- 

 finity of apartments which communicate by small aper- 

 tures ; at others by small light cylindrical pillars fur- 

 nished with a base and capital which are arranged in 

 colonnades, leaving a communication perfectly free 

 throughout the whole extent of the story''. 



Two other tribes of carpenter ants (F. cethiops and 

 F.fiava, Latr.) use sawdust in forming their buildings. 

 The former applies this material only to tlie building 

 of walls and stopping up chinks : the latter composes 



" Hubcr, Eecheichcs, &c. 45. " Ibid. 53. 



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