14 THE ZOOLOGIST. 
STRIDULATION IN SOME AFRICAN SPIDERS. 
By R. I. Pocock, of the British Museum. 
To most readers of ‘ The Zoologist’ the Spiders which form 
the subject-matter of the following pages are probably best 
known by the comprehensive title ‘‘ Mygale,” a term which 
was applied to the group of which they are members in the 
first decade of this century, and has been almost up to the 
present time universally adopted for them by the compilers of 
text-books, and the writers of articles on popular natural history. 
They are also sometimes called Crab-Spiders, presumably from 
the great size to which most of the species attain; sometimes 
Bird-eating Spiders, from their alleged propensity for capturing 
and devouring small birds, a propensity which suggested to 
Lamarck the generic term Avicularia, still in use for one of the 
South American genera. But during the last fifty years our 
knowledge of this group has increased by leaps and bounds; the 
genus has expanded into a family, represented by numbers of 
genera which are rapidly becoming more and more accurately 
defined and classified. 
Apart from their large size and usually heavy build, these 
Spiders, referred to a family variously termed Mygalide, Thera- 
phoside, and Aviculariide, may be recognized from the vast 
majority of other Spiders by possessing two pairs of lung-sacs, 
and by the circumstance that the mandibles or jaws project 
horizontally forwards; while the fang closes almost longitudinally 
backwards. } 
So far as habits are concerned, it may be added that none of 
the species spread nets for the capture of prey. Most of them 
live on the ground beneath stones, or in deep burrows which they 
excavate in the soil, and line with a layer of tough silk to prevent 
the infall of loose particles of earth or sand. At nightfall the 
Spiders may be seen watching at the entrance of their burrows 
for passing insects, and during the breeding season the females 
