166 Mr. W. 8. MacLeay on the Anatomy of the 
to prove it. Mr, Kirby is undoubtedly wrong in imagining it to belong 
to the mesothorax, but perhaps not so much in urging that this piece is 
without a representative in Coleoptera, It would however be contrary to 
every rule of generalization to suppose that the Hymenoptera could have 
any piece peculiar to themselves.* Nature, as I before said, works in 
inferior groups with a given quantity of materials. I have already 
shewn the tergum of the prothorax to be, at its maximum of develope- 
ment, composed of four pieces, If these four pieces should be nearly 
equally developed we have a Locusta. If the prescutum and scutum 
should be greatly developed the other two pieces will disappear, and we 
shall have the generality of Coleoptera ; while, on the other hand, if the 
scutellum or postscutellum should be developed considerably, then the 
other pieces will disappear, and we shall have an Hymenopterous insect. 
Now certainly more than one piece exists in the tergum of the prothorax 
of Hymenoptera. Vor the prescutum and scutum of the prothorax, i.e. 
the pieces which represent what is vulgarly called the thorax of the Cole- 
optera, do not entirely disappear in Hymenoptera as Mr. Kirby says,t 
since on passing the point of a scalpel under the fore legs of a common 
Wasp, and so breaking off the prothorax with the head, we shall per- 
ceive the ring of the prothorax complete, although it is only represented 
by the ligamentous membrane which connects the two epimera.§ This 
* See Int. to Ent, Vol. IL, p. 549. This notion is borrowed from Chabrier, 
who, however, does not go so far as Mr. Kirby, and fancy that it belongs to 
the mesothorax, His words are, ‘la piéce supérieure du prothorax ou le 
*¢*collier,’? 
+ Asa corollary from this, it follows that the Coleoptera which come near- 
est to the Hymenoptera, are those, the prescutum of whose prothorax is most 
evanescent, and whose seutellum of the same is most developed. 
{ See Int. to Ent, Vol. IIL. p. 535, 
§ There is one insect, however, which makes me rather doubt whether the 
structure of the Hymenopterous thorax may not be still nearer to that of Co- 
leoptera than is stated above, IT allude to the Agaon paradowum of Dalman, If 
this author’s figures be correct, then that most singular Hymenopterous Insect 
has the thorax of a Coleopterous one, the prothorax being exceedingly deve- 
loped, and the rest of the thorax proportionably small. There is, perhaps, 
little doubt of Latreille being right in making the Chalcide come the nearest 
to the Strepsiptera, Xenos being almost an Hymenopterous genus. 
