584 EXTERNAL ANATOMY OF INSECTS. 
the internal processes of the breast of insects: these con- 
sist for the most part of the endosternum, or internal 
sternum, and its branches. As the principal feature of 
this are the processes which rising from it serve as points 
of attachment to the muscles that move the legs, &c., I 
shall confine myself to them ;—they are, the antefurca, 
the medifurca, and the postfurca. 
1. Antefurca». ‘The first portion of the endosternum, 
or the internal prosternum, branches into the antefurca. 
In the Coleoptera a plate varying in shape and direction? 
sends forth a pair of mostly vertical processes of a car- 
tilaginous substance‘, differing in height in different 
genera. In the ground-beetles there is neither this plate 
nor its processes ; but in the water-beetles the latter are 
very visible. A very singular and complex machine re- 
presents the part we are considering in that extraordi- 
nary insect the mole-cricket (Gryllotalpa). When we 
look at its prodigious arms and consider their office’, 
we may imagine that the requisite apparatus for moving 
them must be very powerful and peculiar.. Their Cre- 
ATOR has accordingly provided them with a machine for 
this purpose more than usually complex, extending from 
the prothorax to the prosternum ; the former being its 
base, and the latter its verter. ‘The cavity of the mani- 
trunk is divided longitudinally by a double cartilaginous 
partition surmounted by a bony frame, with an anterior 
condyle or tuberosity, with which the inner part of the 
base of the clavicle of the arm appears to ginglymate; 
and the manitrunk is preserved from the injury the pow- 
erful action of the arm might occasion, by the counter- 
@ Plate XXII. Fic. 7. > Thid. a. © Tbid. e'. 
“ See above, Vor. I. p. 193. and IL. p. 254, 362. ' 
