In the course of a special description of these sense-organs in the Orthoptera, Hauser describes at length those of _Œdipoda cœrulescens_ and _Caloptenus italicus_. On one antennal joint of Caloptenus (Fig. 268) was often counted 50 pits; on the anterior joints the number diminishes to about 30. Hauser thinks that in all Orthoptera whose antennæ are like those of Caloptenus occur similar pits, as he found them in Stenobothrus (Fig. 269) as well as in Œdipoda. Gryllotalpa possesses similar pits,—four to six on each antennal joint, making between 300 and 400 pits on each antenna.[48] In _Mantis religiosa_ the pits were not detected, but on each joint, except the eighth basal, there are about 200 small, hollow, curved teeth with a fine opening in front. In the Neuroptera (Chrysopa) there occur on the antennæ, besides numerous very long tactile bristles, small pale, transparent teeth. No pits could be detected. In the Hemiptera (two species of Pyrrhocoris only were examined) only two kinds of tactile bristles occurred, but Hauser detected no pits, though Lespès states that they are present. [Illustration: FIG. 272.—Longitudinal section of apex of palpus of _Pieris brassicæ_: _sch_, scales; _ch_, cuticula; _hyp_, hypodermis; _n_, nerve; _sz_, sense-cells; _sh_, sense-hairs.—After Vom Rath, from Sharp. ] Of the Diptera, Hauser examined more than 60 species. The pits in the _Diptera brachycera_ (Muscidæ, etc.) are unexceptionally confined to the third antennal joint. Their number varies extraordinarily in the different species. _Helophilus florens_ has on each antennal disk only a single pit, while _Echinomyia grossa_ possesses 200 of them. In flies of certain families the pits are compound, and contain 10, 20, and often 100 olfactory hairs, partly arising from the coalescence of several pits. Such pits are usually divided by lateral walls into several chambers, whose connection is only indicated by their common outlet. Simple olfactory pits with a single olfactory style were observed only in the Tabanidæ, Asilidæ, Bombylidæ, Leptidæ, Dolichopidæ, Stratiomyidæ, and Tipulidæ. In the last the compound forms do not occur at all, but in the other families mentioned also occur compound pits, receiving from two to ten nerve-terminations. The antennal pits of flies are always sac-like invaginations of the external chitinous integument, of manifold shapes, opening externally and never closed by a membrane. The pits differ but slightly in the different species, and that of _Cyrtoneura stabulans_ (Fig. 273) is described at length as typical of those of brachycerous flies in general.