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 Mygalidæ, Theraphosidæ, and Aviculariidæ, 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
