EXTERNAL ANATOMY OF INSECTS. 549 
the lower part of the manitrunk *, should represent the 
antepectus, and have the arms inserted in it; but in the 
case before us there is a distinct antepectus bearing the 
arms received by the socket formed by this annulus. But 
the most powerful argument is the fact that some insects 
have both the prothorax and collar, a circumstance that 
completely does away every idea of their identity. If 
you examine the common hornet (Vespa Crabro), or any 
saw-fly (Serrzfera), you will find, as was before intimated, 
that the real covering of the cavity of the manitrunk is a 
ligamentous membrane, which properly represents the 
prothorax. In another genus of the same order (Xiphy- 
dria), the sides of the antepectus turn upwards and nearly 
form a horny covering distinct from the collar>, the 
ligamentous part being reduced to a very narrow line, 
and in Fenus the dorsal fissure is quite filled up, so that 
in this the manitrunk is perfectly distinct, and exhibits 
both prothorax and antepectus of the usual substance. In 
Nomada likewise, N. Goodeniana was the species I ex- 
amined, there is a short minute prothorax besides the 
collar. Next let us turn our attention to the Diptera ; if 
you examine the common crane-fly ( 7zpula oleracea), you 
will find, first, a regular short prothorax, to which the 
antepectus, with the arms, is attached; and behind this also 
is a short collar embracing the alitrunk anteriorly. The 
next insects that I shall mention, as exhibiting both pro- 
thorax and collar, are the Libellulina. ‘These are generally 
admitted to have the former of these parts °, but besides 
this they have also the latter, which is the most ample 
and conspicuous piece in the whole trunk"; intervening, 
* See above, p. 534, > Prare IX. Fie. 14, 
© Ibid. Fic. 6. a. 4 Ibid. Fie; Fig’. 
