COCKROACHES, ETC. 127 



like a man shod with snow-shoes running along on 

 the surface of the snow. 



One other aquatic Orthopteron may be mentioned, 

 the Brazilian Stick-Insect, Prisopus flabelliformis. This 

 curious-looking creature hides under stones in moun- 

 tain-streams. 1 The under-side of the body is hollowed 

 out and is fringed with long hairs. It has been 

 supposed that the air is expelled from this hollowed- 

 out portion of the body, and a vacuum being formed 

 the pressure of the water keeps the insect closely 

 applied to .the stone on which it is resting. I think 

 it is far more likely that a store of air is held in the 

 hollow beneath the body, and that the insect is enabled 

 to cling to the stone by means of the sucker-like pads 

 known as pulvilli that are found on the tarsal joints, 

 otherwise it is difficult to see how the insects can 

 breathe. 



Very closely related to the Cockroaches are the 

 Praying Mantises, quaint hobgoblins of insects of 

 which only a few species occur in Europe, though 

 they are abundant enough in the tropics. I kept many 

 specimens in captivity during my time in Sarawak, and 

 found that they made interesting pets. They were fed 

 on a diet of insects which is their natural food, and 

 some individuals would become comparatively tame, 

 that is to say they could be held in the hand and 



* These " aquatic habits," described by Murray, have been shown 

 by C. J. Gahan to be a delusion. A closely allied species, P. fisheri, 

 exhibited by him at the Ent. Soc., London, December 6, 1911 

 (Proc. Ent. Soc., 1911, p. Ixxxiii), possessed the same adaptive features 

 as P. flabelliformis, and yet it had been taken on a tree or a sapling. 

 Furthermore, Gahan showed that these features are such as to 

 promote concealment on lichen-covered bark. E. B. P. 



