MOTIONS OP INSECTS. 



hoppers with setaceous antennae (Acrida) have four tarsal joints. Those 

 with filiform antennae (Locusta and Acrydium), those with ensiform 

 (Truxalis '), and the crickets (Gryllus), have only three. In Blatta, the 

 variations with respect to the suckers and cushions (for many species are 

 furnished with both) are remarkable. The former in some ( Blatta giganted) 

 are altogether wanting ; in others (J?. Petiveriana) they are mere rudi- 

 ments ; and in others (B. Maderce) they are more conspicuous, and re- 

 semble those of the Gryllidts. The foot- cushions also in some are nearly 

 obsolete, and occupy the mere extremity of the four first tarsal joints 

 (B. 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 (B. gigantea, &c.), they extend the length of the four 

 first joints, and are very conspicuous. In some (B. Mouffetl K.) 2 , 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 orbi- 

 cular 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 movable processes attached to the base of 

 the first joint of the tarsus, which probably act as suckers. 3 In this genus 

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

 of the two following ones. 4 The species of the genus Locusta come next. 

 This genus is called Acrydium by Latreille after Geoffrey j but, since it 

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

 to the tribe to which it belongs. 5 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 6 ; and the same conformation also distinguishes 

 the feet of Truxalis. In the species of Acrydium F. (Tetrix Latr.), the foot- 



of one side have only four joints, while the intermediate one has five. On the other 

 side the hind leg is broken off, but the anterior and intermediate tarsi have both 

 five joints. In another specimen one posterior tarsus has four and the other five 

 joints. 



1 The name of this genus, properly spelled, is Troxallis, from the Greek T^!*AA/? , 

 Gryllus. 



2 This insect, which is remarkable for having the margin of its thorax reflexed, 

 was long since well figured in Mouffet's work (130. fig. infima). It has not, how- 

 ever, been described by any other author I have met with. It is common 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. 



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

 this genus and Locusta, and the claw-sucker in the latter, which he thinks are 

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



4 Philos. Trans. 1816. t. xxi. f. 813. 



5 See Zool Journ. for 1825, No. iv. 431. 

 e Philos. Trans. 1816. t. xxi. f. 19. 



