EXTERNAL ANATOMY OF INSECTS. 5i5 



may see in a Chinese chafer (Mimela K.), which imi- 

 tates the external appearance of a quite different tribe a ; 

 in others again it is behind them, as in most of the Lamel- 

 licorn beetles. In the common dung-chafer (Geotrupes 

 stercorarius), it is a hairy process, which, when the head 

 is bent downwards, is received by a deep cavity of the 

 mesosternum. The Dynastidce MacLeay may always 

 be known by a columnar presternum rising vertically be- 

 tween the arms and the medipectus. Lastly, in other 

 tribes there is a prosternal elevation both before and be- 

 hind the arms, as in Cerambyx thoracicus, dimidiatus, and 

 affinities. Of the second description, those that have a 

 less elevated horizontal presternum, the point in most is 

 to the anus, but in some to the head, : thus in Carabus L. 

 it is generally a subspathulate flat piece, the point of 

 which slides over the mesosternum, or covers it; but in 

 Harpalus megacephalus Latr. b , one of this tribe, though 

 similarly shaped, its point is to the head. These hori- 

 zontal prosterna vary in their termination. In that of 

 Carabus L. the apex is obtuse ; in that of Elater, above 

 described c , and Dytiscus it is acute -, in Prionus lineatus, 

 Spencii K., &c, it is bilobed; and in Buprestis variabilis, 

 attenuata, &c„ obsoletely trilobed. With regard to the 

 other Orders no striking features of this part are observ- 

 able, except in some Orthoptera. In Acrida viridissima 

 K. {Locusta F.) it is represented by two long filiform ver- 

 tical processes ; and in Locusta Leach by a single coni- 

 cal horn d , mistaken by Lichtenstein for a process of the 



a Kirby in Linn. Trans, xiv. t. iii,/. 4. i. 



b It is doubtful whether M. Latreille's Harpalus megacephalus is 

 synonymous with Carahus megacephalus Fab. Coinp. Gen. trust, et 

 Ins. i. 206. with Syst. Eleuth. i. 187. 95. 



c Vol. II. p. 317—. d Peate VIII. Fig. 11. b, 



yoL. in. 2 n 



