MOTIONS OF INSECTS. 



265 



in some {Blatta gigantea) are altogether wanting ; in others 

 (B. Petiveriana) they are mere rudiments ; and in others 

 (2?. Madera) they are more conspicuous, and resemble those 

 of the Gryllidce. The foot-cushions also in some are nearly 

 obsolete, and occupy the mere extremity of the four first 

 tarsal joints (i?. orientalis, Americana, Capensis, &c). In 

 B. Petiveriana there is none upon the first joint ; but upon 

 the extremity of the four last, not excepting the claw-joint, 

 there is a minute orbicular concave one, resembling a sucker. 

 In others (i?. gigantea, &c.) they extend the length of the 

 four first joints, and are very conspicuous. In some (B. 

 Mouffeti K. 1 ), which have no 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 colour ; but in one specimen of a hairy female which 

 I have, from Brazil, they are black. The spectre genus 

 (Phasma) 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 Phasma. 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. 2 In this genus there are two foot-cushions on the 

 first joint of the tarsi, and one on each of the two following 

 ones. 3 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 



1 This insect, which is remarkable for having the margin of its thorax re- 

 flexed, was long since well figured in MomTet's work (130. Jig. ivfima). It has 

 not, however, been described by any other author I have met with. It is com- 

 mon in Brazil. Some specimens are pallid, while others are of a dark brown. 

 It is to be observed that the Blattina are resolvable into several genera. 



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

 in this genus and I.ocusta, and the claw-sucker in the latter, which he thinks are 

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



3 Philos. Trans. 1816, t. xxi. f. 8—13. 



