rarely longer than the abdomen (male Astata). The coLtar* 
in the first families, is laterally prolonged as far as the 
origin of the wings, embracing the mesothorax in a semi- 
circle, it is rarely truncated anteriorly (Mutilla, Sapyga), and 
occasionally prolonged into a kind of neck (Ammophila, 
Miscus). In the last families it is very narrow and trans- 
verse. The clavicula of M‘Leay and Chabrier appears to 
me to be distinct from the TUBERCLE of Kirby. In the 
thorax of the two insects, which the former author has 
figured to elucidate his and Audouin’s theory, the tubercle 
is almost obsolete, as is the case in the Vespade generally, 
and in all which have the collar extending laterally to the 
origin of the wings. Its situation also varies with the form 
of the collar, it is most remote from the wings and most 
developed in such as have the collar narrow and transverse, 
and its colour sometimes affords a subsidiary specific 
character. I consider that it forms a cover or case for the 
anterior spiracle, the aperture to which varies in the several 
genera and is always indicated by the cilia or short stiff 
hairs with which one of its margins is fringed. It is always 
smooth and shining, frequently coloured, and is, I think, 
the corps calleux of St. Fargeau; it is always attached by 
one side to the sutural separation from the collar, I suspect 
it has some slight degree of motion and that it articulates 
with it. The TecuL# also afford frequently a subsidiary 
specific character, but their colour, as well as that of the 
tubercles, is not constant; they are very large in the male 
of Mutilla, moderately so in Tiphia, and very small in 
Pompilus. But the METATHORAX will be found a more im- 
portant portion of this division of the body in this tribe, 
* T always use this term with Mr. Kirby, it is synonymous with Burmeister’s 
pronotum and well explains the part in this order, the terms of other writers are 
too circumlocutory. 
