Discussion

• (1) The Rhaphidophoridae exhibit a wide range of variation in the number of spines on the legs, and it is unfortunate that Hutton, partly through lack of specimens, should have used this character so extensively to form new species within the group.

• (2) In general, apical spines are a more reliable character for the establishment of genera and species within the family; but in Talitropsis crassicruris apical spines may or may not be present on the fore, middle and hind femora.

• (3) Sexual dimorphism is often exhibited by members of the family; but it is poorly developed in the two species discussed in this paper.

• (4) The shape of the external genitalia is remarkably constant in both species.

• (5) Neither N. serratum nor T. crassicruris have been adequately illustrated. Hutton's type description of N. serratum in 1904 is without any figures, while his description of T. crassicruris is illustrated with very small drawings of the male subgenital plate and the apex of the hind tibia. Miss Lysaght has drawn the “supragenital plate” of the male and the supra-anal plate and hind tarsus of the female of N. serratum, but these drawings are not typical of the species. T. crassicruris is illustrated much more fully by her than by Hutton, but not very accurately.

• (6) Attention is drawn to two small tubercles situated medianly on sternite VII, just proximal to the subgenital plate. The function of this appendage is unknown, but it may be an accessory to the external genitalia during the mating of the wetas. It is present only in females, and not always then, so that it is not a specific character, but variable.

• (7) The habitats chosen by these two species of cave-weta may be correlated with the size, structure and spination of the hind legs. N. serratum with its short, thin, weak hind tibiae armed with numerous very small spines, inhabits petrel burrows or hollows under stones, where its home, with the conditions it requires, is already