Thorax in winged Insects. 175 



which have not been distinguished by Mr. Kirby. Between the episterna 

 and the squaniulse is a small piece called by M. Chabrier the clavicle. It 

 is not, however, the clavicula of Mr. Kirby. As however it, hke the 

 squamula, does not properly be]ong to the thorax, being a rudimentary 

 bone of the wing, I shall not say more of it until I come to treat of the 

 Comparative Anatomy of the Wings of Insects in a future paper.* 



4. The epimera of the meso thorax are two sub-quadrangular pieces. 

 Three of the sides of an epimeron are bounded by the episternum of the 

 mesothorax in front, by the mesosternum below, and by the pectus of the 

 metathorax behind ; the upper side being bounded by the rudimentary 

 bones of the wing and by part of that lateral process of the postscutellum 

 of the mesothorax which joins the scutellura of the same. In my draw- 

 ing of the medipectus I have carefully avoided representing any part of 

 the postscutellum, because it belongs to the tergum. The point of junc- 

 tion, however, with the epimeron is marked. f Mr. Kirby has noticed 

 the epimera when he very correctly states that " in Vespa a small sub- 

 " triangular piece just below the base of the upper wing is probably 

 " analogous to the scapularia in Coleoptera ;" smpularia being appa- 

 rently his name for the epimera of the mesothorax. 



3. Of the Pectus of the Metathorax. 



This consists of the usual parts, but I cannot here pretend to make 

 Mr. Kirby's nomenclature harmonize with M. Audouin's. I shall there- 

 fore describe the parts in the usual way. 



1. The meiasternum is subquadrate, carinated above, and having a 

 small slit below in the middle. The anterior angles are elevated. It is 

 a very conspicuous piece, yet Mr. Kirby denies its existence.^ 



2. The postfurca is composed of two branches, which run off from 

 a strong base to meet the junction of the metasternum with its episterna.§ 



3. The episterna are two sub-triangular pieces, each situated close 



* The first pair of stigmata are situated-between the collar and the clavicles 

 of M. Chabrier. See fig. I, y. 

 t Fig. 9, R. 



X Fig. 5 and 10. P. Also see Int. to Ent., Vol. Ill,, p. 383. 

 § Fig. 10, W. 



