EXTERNAL ANATOMY OF INSECTS. 585 
action of this machine, to describe which fully, would 
demand more space than I can afford*. I mentioned 
under the mesostethium, the apertures visible in the breast 
of Locusta and Acrida. Each of these apertures opens 
into an internal, tubular, horny process, which arching 
off is attached at the other extremity to the sides of the 
trunk—a pair being appropriated to each segment; the 
first analogous to the antefurca, the second to the medi- 
Jurca, and the last to the postfurca. In the medipectus 
and postpectus of Acrida viridissima there is only a single 
aperture, terminating in a single tube, which after rising 
vertically a little way sends off a branch on either hand 
to the sides of the trunk. Where there are three of 
these holes, as in the antepectus and medipectus of Lo- 
custa Dux, there are three of these processes, the inter- 
mediate one being vertical. In the subsequent Orders 
the processes of the endosternum are not sufficiently re- 
markable to require particular notice: my further ob- 
servations upon them will therefore be confined to the 
Coleoptera Order. 
2. Medifurca’. ‘This part, which belongs to the mid- 
legs, is in many cases more conspicuous than the ante- 
furca. In Copris Molossus the endosternum of the medi- 
pectus is represented by a transverse zigzag ridge* be- 
tween the sockets of the mid-coxz, from which proceeds 
a pair of branches wide at the base and growing gra- 
dually more slender to the extremity‘, which is attached 
to the sides of the trunk; in Dyééscus marginalis a pair 
* This machine is described by Dr. Eschscholtz, Beitrige zur 
Naturkunde, &e. Heft. i. 24—. t. i. ii. See also Professor Kidd in 
Philos. Trans. 1825. no. x. #. xv. fa 3, 4. 
> Pirate XXII. Ere. 6: “Ibid. Fic. 6. a. 4 Tbid. b. 
