Thorax in winged Insects. 169 
Mr. Kirby’s “ most powerful argument’ for the collare not belonging to 
the prothorax is the fact that in Vespa and certain other insects, where the 
mesothorax is excessively developed, there is both a prothorax (meaning 
thereby a scutum) anda collare.* And so there would be in the pro- 
thorax of every winged insect, if perfectly developed, as may be learned 
from the prothorax of a Gryllus, or the study of M. Audouin’s observations. 
Therefore this ‘* powerful argument”’ cuts the wrong way. 
In Polistes the scutellum of the prothorax is emarginate, offering a large 
sinus in the middle, which embraces two sides of the sub-pentagonal 
scutum of the mesothorax. 
2. OFTHE TERGUM OF THE MESOTHORAX. 
1. The prescutum of the mesothorax is the first piece that comes 
under our notice.t Under the name of prophragma it is mentioned by 
Kirby as existing in Hymenoptera, and so separating, as it ought to do, 
the collare from the scutum of the mesothorax. It is an internal and 
vertical piece.t 
2. The scutum, whether the collar be apparent or not, is therefore the 
second piece of the mesothorax.§ It appears externally joined to the 
collare, the sides of which embrace it. It is, as Mr. Kirby observes, ex- 
cessively developed in Hymenoptera, and forms indeed the most con- 
spicuous piece of the thorax.|| 
3. The scutellum of the mesothorax, the third piece,{{ and also 
externally conspicuous in our Polistes, follows the scutum.** It is the 
postdorsum of M. Chabrier. 
* From this remark it would appear that Mr. Kirby is not aware that the 
prothorax is a compound piece as well as the mesothorax and metathorax. 
+ Fig. 4 and fig. 5, E, t See Int. to Ent. Vol. II. p. 549. 
§ Fig. 4 and fig, 5, F. 
|| By looking at some Hymenoptera, where this piece is most developed, it 
would almost seem to be composed of three confluent pieces, the two lateral 
yet requiring aname, I suspect, however, not having yet dissected a Chalcis 
carefully, that these last pieces are a third pair of paraptera, possibly those be- 
longing to the prothorax, pushed out of their proper place. 
q Fig, 4 and fig. 5, G. 
** On the subject of this piece, Mr. Kirby gives his only citation of M. 
