1815.) On the Uses of the Dorsal Vessel. 35 
pectoral tracheze proceed from the common trunk, which takes up 
air in the first stigma of the abdomen. 
In general the arterial trachese are very much branched, and give 
out an infinite number of ramifications. This disposition is very 
striking in the genera of which we are speaking, and which are dis- 
tinguished by the position of their stigmata. These stigmata are 
placed below the e/ytres, and on the sides of the body in the back. 
It may be owing to the diffieulty which the air finds to introduce 
itself into these stigmata, especially when they are concealed below 
immoveable elytres, as in the blaps, that the arterial trachez are so 
disposed that all parts of the body speedily enjoy the influence of 
the air. These stigmata are formed in the common way by a 
jutting out horny border of considerable thickness. Their opening 
is oval, and their greatest diameter is in a transverse direction. It 
is easy, by opening them, to perceive the common trunk of the 
arterial tracheze, which opens there. The disposition of the arterial 
trachez in the cebrio longicornis is almost the same as in that which 
we have just described. 
In the phalangium and analogous genera, only a single order of 
trachez is observed. ‘The respiratory system in these genera may 
be considered as formed of common trunks, which, situated in the 
neck, are the centre from which all the other ramifications proceed. 
These common trunks are found near the stigmata, to which they 
send a branch ; and from this point proceed two bundles of trachea, 
which spread over all the body, especially the intestinal viscera. 
We see even that they surround each appendix of the intestinal 
tube, and their first membrane is in part formed of these trachea. 
The common trunks continue thus along the sides of the body, 
giving out different branches to the muscles of the legs, to the 
mouth, to the dorsal vessel, and to the organs of generation. This 
respiratory system is one of the simplest. Only two stigmata exist, 
placed on each side of the corcelet, on the same line as the fourth 
pair of legs. ‘hese stigmata are oval, the greatest diameter pro- 
ceeding from below upwards. Internally we see: that they have a 
border pretty strong. ‘They are very large, compared to the size of 
the body. 
The larvee of lepidopteres, or caterpillars, have likewise nothing 
but arterial trachee. Lyonnet,* to whom the anatomy of insects 
is so much indebted, had already remarked this fact. However,. I 
thought it worth verifying in the caterpillars of different butterflies, 
especially in those of the cabbage and of fennel; in the larvee of the 
tombyx pavonia major; mori, and in that of the sphina atropos. In 
all these £ found only arterial tracheae. When there are only arterial 
trachee, we see them always formed by a common svete, which 
opens into the stigmata, and from which numerous ramifications 
‘proceed, which are distributed to all parts of the body. This 
common trunk extends from one extremity of the body to another, 
* See Traité Anatomique dela Chenille du Saule, p. 101 and 237, tab. x. fig. & 
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