HYMENOPTERA. 75 
the wings; the only portion visible from above (except in a few spe- 
cies, which have an elongated neck, as Xiphydria, &c.) being the part 
which is usually termed the collar, having its posterior margin 
arched, and sometimes extending to the base of the fore wings, and 
forming the front of the upper portion of the thorax. It is, however, 
so much detached from the remainder of the prothorax, that Mr. 
Kirby considered it as not belonging thereto, but as an organ, sui 
generis ; Messrs, MacLeay and Audouin, however, agree in regarding 
it as a portion of the prothorax, although they differ as to its exact 
analogue. (Consult Kirby and Spence, Jntrod., vol. iii. p. 549., Mac- 
Leay’s Memoir in the eighteenth number of the Zool. Journ., Audouin’s 
translation thereof, with additional notes, in the Ann. des Sciences 
Natur., tom. xxv., Haliday, in Entomol. Maq., vol. v. p.212., and Bur- 
meister’s Manual, English edition, p. 78.) The two other thoracic 
segments are united into a mass; the mesothorax, from bearing the 
largest pair of wings, being more extensively developed than the me- 
tathorax, and bearing on its upper surface a conspicuous plate, which 
is the mesothoracic scutellum; and at the base of the fore wings is a 
pair of small corneous pieces, termed tegule. According, however, 
to Audouin and Latreille, the terminal portion of the thorax, in which 
a pair of lateral spiracles is observable, is the real representative of 
the basal segment of the abdomen (in those species which have the 
abdomen pedunculated) ; the metathorax itself being supposed to be 
reduced, above, to a narrow arch, whilst the first apparent segment 
of the abdomen, forming the peduncle in certain groups, is, in effect, 
the second abdominal segment. Messrs. Kirby, MacLeay, Saint 
Fargeau, and Burmeister, however, consider this spiracle-bearing por- 
tion as the termination of the metathorax ; and I have clearly shown, 
in a memoir upon the anatomy of the earwig, published in the Zrans- 
actions of the Entomological Society, vol.i., that the metathorax is pro- 
vided witha pair of spiracles.* Ina memoir, published in the twenty-fifth 
number of the Hntomological Magazine, I have also endeavoured to 
prove that the hind part of the thorax in the petiolated Hymenoptera, 
cannot be regarded as abdominal ; and, in a subsequent page, under the 
* Consult Latreille (Fam. Nat., p. 259.), Cuvier (Rapport, on Audouin’s Mé- 
moire, p. 11.), MacLeay, (in Zool. Journ., No. 18.), Audouin (in Ann. Soc. Nat., 
tom. xxy.), Burmeister (Manual, p. 85.), Saint Fargeau (Hist. Nat. Ins. Hymén., 
tom. i. p. 78.). 
