EXTERNAL ANATOMY OF INSECTS. 579 



come to the Neuroptera — in the Libellulina it consists of 

 two pieces, like those of the scapulars, but smaller a , and 

 Its inclination is towards the head : in Panorpa also it 

 resembles the scapulars both in form and other circum- 

 stances b . In the remaining Orders it exhibits no very 

 remarkable features. 



16. Metasternum b . The central part of the mesoste- 

 Ihium when elevated or porrected, or otherwise remark- 

 able, is called the metastemum. In the Coleoptera, in 

 those cases, as we have seen above c , in which the me- 

 dipectus and postpectm form one piece, its anterior point 

 becomes the mesosternum ; but in others, as the Preda- 

 ceous and Capricorn-beetles, &c, it is received in a sinus 

 or fork of that part, or meets it. It is usually neither 

 so remarkable nor important as the mesosternum. In 

 Bolbocerus K. it is a rhomboidal elevation : in Gyrinus a 

 ridge; 4xs also in many Hydrophili, in which it passes 

 between the hind-legs to the abdomen, and terminates in 

 a sharp point d ; and in Dytiscus its two diverging lobes 

 cover the base of the posterior trochanters e . In the 

 Orthoptera Order this part is not remarkable; but in 

 Acrida viridissima K. it consists of three triangular pieces, 

 the lateral ones being erect, and the intermediate one ho- 

 rizontal: in Locusta Leach it resembles the mesosternum*. 

 In the Heteropterous Hemiptera the whole mesostethium 

 is elevated, and terminates at both ends in a fork, the 

 anterior one receiving the point of the promuscis, and the 

 posterior one that of the epigastrium .• in the Homopte- 

 rous section, the Tettigonice F. have usually a distinct me- 



* Plate IX. Fig. 8. &'. b Plates VIIL IX, a f. 



c See above, p. 565. d Plate VIIL Fig. 8. a f . 



c De Geer iv. U iv.f. 3. dd. ee. f Plate VIIT. Fig, 13, a f. 

 2 F 2 



