162 Mr. W. S MacLeay on the Anatomy of the 



wing where these exist. It is called the dorsolum by Kirby,* having 

 been previously called dorsum by Chabrier. 



3. The scutellum is that part the external appearance of which is com- 

 monly so called by entoraologists.f 



4. The postscidelhim is a piece almost always completely concealed 

 in the interior of the thorax, sometimes confluent with the inner face of 

 this so as to be confounded with it, and sometimes being free. It is called 

 frcenum by Mr. Kirby, J but this naturalist only knew it in certain orders. 



The above four pieces when united form the tergum of the mesothorax. 



The eight inferior or pectoral pieces of the viesothorax are the meso- 

 sternum, K., medfurca, K., two episterna, A., two epimera. A., and 

 two paraptera. A.; the six latter pieces being lateral and the paraptera 

 often so situated as to appear to belong to the tergum. 



1 . The mesosternnm is exactly to the mesothorax what the prosternum 

 is to the prothorax. It is therefore called by Audouin the sternum of the 

 mesothorax.^ 



2. The medifurca is well explained by Kirby.jl It is to the meso- 

 thorax what the antefurca is to the prothorax. Therefore Audouin calls 

 it the entothorax of the mesothorax. 



3. The episterna are two pieces exactly analogous to those of the pro- 

 thorax, and have in general similar relative positions. 



4. The epimera are exactly analogous to those of the prothorax, and 

 have likewise similar relative positions. 



5. The paraptera are two lateral pieces having a relation to the 

 wings. They are usually supported by the episternum, but in general 

 are little developed or are even evanescent. Their situation is always near 

 the wing, of which indeed they more properly form part.^ 



* See Int. to Ent. Tab. 22, fig. 8. i'. The scutum of the mesothorax in cer- 

 tain Hymenopterous Insects requires further examination than I can give it in 

 this paper, and I shall therefore return to the subject at some future opportu- 

 nity. 



t See Int. t,o Ent., Tab. 22, fig. 8. k'. 



X See Int. to Ent., Tab. 22, fig. 8. T. 



§ See Ann. des Sc. Nat., Tom. 1, pi. 8. 



il See Int. to Ent., Vol. III. p. 587, Tab. 22, fig. 6. M. Cuvier calls it " la 

 " piece en forme d'y grec." 



% In Hymenoptera the parapteron is generally above the wing; in Coleop- 



