THORAX 



103 



wing of a Hymenopteron. One of them becomes of considerable 



size and importance in the Order just mentioned, and seems 



to be articulated so as to exert pressure on the base of the 



costa of the wing. This structure attains 



its maximum of development in a genus 



(? nondescript) of Scoliidae, as shown in Fig. 



56. The best name for this sclerite seems 



to be that x^roposed by Kirby and Spence, 



tegula. Some writers call it paraptere, hypo- 



ptere, or squamule, and others have termed 



it patagium ; this latter name is, however, 



inadmissible, as it is applied to a process of 



the prothorax we have already alluded to. 



To complete our account of the structure 

 of the thorax it is necessary to mention cer- 

 tain hard parts projecting into its interior, 

 but of which there is usually little or no trace externally. A 

 large process in many Insects projects upwards from the sternum 

 in a forked manner. It was called by Audouin the entothorax ; 

 some modern authors prefer the term apophysis. Longitudinal 

 partitions of very large size, descending from the dorsum into 

 the interior, also exist ; these are called phragmas, and are of 

 Q J, great importance in some Insects with 



perfect flight, such as Hymenoptera, 

 Lepidoptera, and Diptera. There is no 

 phragma in connection with the prono- 

 tum, but behind this part there may 

 be three. A phragma has the appear- 

 of the dorsum ; it 

 attachment for muscles. 



Fig. 56 . — Head and 

 thorax of wasp from 

 Bogota : t, tegula ; b, 

 base of v/ing. 



ance of being a fold 



^ ,„ „ i- r serves as an 



Fig. 57. — Transverse section 01 



skeleton of metathorax of and may probably be of service 



Goliathus druryi, 



seen from 

 behind : a, metanotum ; b, 

 metastemum ; c, phragma ; 

 d, entothorax (apophysis or 

 furca) ; e, apodeme ; /, ten- 

 don of articulation. (After 

 Kolbe.) 



other ways. More insignificant projec- 

 tions into the interior are the little 

 pieces called apodemes (Fig. 57, e) ; 

 these are placed at the sides of the 

 thorax near the wings. The apophyses 

 are no doubt useful in preserving the delicate vital organs from 

 shocks, or from derangement by the muscular movements and 

 the changes of position of the body. 



The appendages of the thorax are («) inferior, the legs ; (J) 



