Reginald Innes Pocock

“ 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 are to be found at its further extremity mounting guard over their egg-cocoon. ”

“ Strictly speaking, however, this is not the case with the stridulating organs that have been found in the Spiders now under discussion; for in all cases these organs consist of modified bristles. In the Oriental members of the family two such organs exist, namely, the one discovered by Wood-Mason, and another discovered by myself in several more genera. [1] In both cases the organ lies between the outer surface of the mandible and the inner surface of the maxilla—the basal segment of the palp; and each consists of a set of vibratile bristles, which are set a-twanging by a series of spines. ”

“ This belief, however, has no foundation in fact; for, in the first place, there is not a particle of evidence that these Spiders possess an auditory sense; and, in the second place, these stridulatory organs are equally well developed in the males and females, and are not, like the sexual stridulating organs known in other groups, confined to the male, or at all events better developed in that sex than in the female. Moreover, they appear in the young at an early age, and become functionally perfected long before the attainment of sexual maturity. ”

“ 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. ”

“ Other species again live in trees, and spin a silken domicile either between forked branches or in the hollow trunk, or in large leaves rolled up for the purpose. There is no doubt that their food consists almost wholly of insects of various kinds. Nevertheless cases are on record of the destruction of small reptiles, mammals, and birds by these monstrous Spiders.
The discovery of stridulatory organs in the members of this family dates back to the year 1876, when Prof. Wood-Mason came across one in an Assamese species now known as Musagetes stridulans. ”

“ Following the palp are the four walking legs, each of which is composed of seven segments, the basal being known as the coxa, and the second, like the second segment of the palp, as the trochanter.
Now these appendages are so arranged that their coxæ, and to a lesser extent their trochanters, are in contact with the corresponding segments of the appendange in front or behind; so that when a limb is raised upwards the adjacent surfaces of the segments in question slide over one another. These surfaces therefore are areas favourable for the development of stridulating organs ”