496 MOTIONS OF INSECTS. 



claw-sucker, there appears to be a cavity in the extremity of the claw- 

 joint, which may serve the purpose of one. These foot-cushions are 

 usually of a pale color ; but in one specimen of a hairy female which I 

 have, from Brazil, they are black. The spectre genus (JPhasmd) exhibits 

 no particular varieties in this respect. The tarsal joints of the legs have 

 cushions at their apex, which appear to be bifid. They have a large orbicular 

 sucker between the claws. In Mantis the fore feet have neither of the 

 parts in question, and the others have no suckers. They have cushions 

 on the four first tarsal joints of the two last pair of legs, which, though 

 smaller, are shaped much like those in Fhasma. In Acrida the feet have 

 no suckers between the claws ; but they are distinguished by two oval, 

 soft, concave, and moveable processes attached to the base of the first 

 joint of the tarsus, which probably act as suckers.^ In this genus there 

 are two foot-cushions on the first joint of the tarsi, and one on each of 

 the two following ones.^ The species of the genus Locusta come 

 next. This genus is called Acrydium by Latreille after GeofFroy ; but, 

 since it includes the true locust, it ought to retain the name Locusta given 

 by Linne to the tribe to which it belongs.*^ All these insects have the 

 terminal sucker between the claws, three foot-cushions on the first joint of 

 the tarsus, and one on the second"*; and the same conformation also distin- 

 guishes the feet of Truxalis. In the species of Acrydium F. {Tetrix Latr.), 

 the foot-cushions, I believe — for in the dead insect they are the reverse of 

 conspicuous — are arranged nearly as in the two preceding genera, but 

 these insects are without the claw-sucker. And lastly, Gryllus has neither 

 suckers nor cushions. From this statement it seems to follow — since 

 Blatta, Phasma, and Mantis, th^it do not leap, are provided with cushions, 

 and Gryllus, a heavy tribe of insects that does, are without them — that 

 their object cannot be exclusively to break the fall of the insects that 

 have them. And for the same reason we may conclude that they must 

 have some further use than augmenting their elasticity when they jump. 

 When we consider that the Blattce, many of which have no suckers, or 

 very small ones, are climbing insects (I have seen B. Germanica run up 

 and down the walls of an apartment with great agility), and that the long 

 and gigantic apterous spectres, &;c. (Phasma) require considerable means 

 to enable them to climb the trees in which they feed, and to maintain 

 their station upon them, we may conclude that these cushions, by acting 

 in some degree as suckers, may promote these ends. 



Amongst the homopterous Hemiptera, Chermis and many of the Cer- 

 copidcB^ are furnished with the claw-suckers ; but the noisy Cicada, as 

 well as the heteropterous section, at least as far as my examination of them 

 has gone, have them not. De Geer has observed, speaking of a small fly 

 of this order {Thrips physapus), that the extremity of its feet is furnished 

 with a transparent membranaceous flexible process, like a bladder. He 

 further says that when the animal fixes and presses this vesicle on the sur- 

 face on which it walks, its diameter is increased, and it sometimes appears 

 concave, the concavity being in proportion to the pressure ; which made 



1 De Geer, iii. 421. t. xxi. f. 13. h. This author has also noticed the cushions in this 

 genus and Locus/a, and the claw-sucker in the latter, which he thinks are analogous to those 

 of the fly. Ibid. 462. t. .xxii. f. 7, 8. 



* Philos. Trans. 1816. t. x.xi. f. 8—13. ^ ^ee Zool Jour, for 1825, No. iv. 431. 



* Philos. Trans. 1816, t. xxi. f. 1—9. * De Geer, iii. 132. 173. 



