534 EXTERNAL ANATOMY OF INSECTS. 
bearing the fore-legs, and containing the muscles that 
move them. 
The prothorax of insects may in general be considered 
with respect to its parts, margin, appendages, shape, 
sculpture, clothing, and proportions. 
1. The prothorax, regarded as a whole, distinct from 
the antepectus or fore-breast, consists commonly of two 
pieces—the shzeld, or upper part*, and the ora, or under 
part’. In the shield you are to observe its apex‘, base*, 
sides*, limb‘, and disk®&. The apex is the part next the 
head ; the base that next the abdomen; the limb the cir- 
cumference, and the disk the central part. In many Or- 
thoptera and Heteropterous Hemiptera, the shield ap- 
pears further to consist of two pieces, an anterior and 
posterior one. The ora isa continuation of the shield 
below the lateral margin, turned downwards and in- 
wards towards the fore-breast and the legs, but separated 
from the former in most cases by a suture, as in the 
ground-beetles (Hwtrechina); and in others merely by 
an impressed line, as in Blaps ; but in the Capricorn 
and many other ‘Tetramerous beetles there is no ora, the 
shield being without a lateral margin, and forming one 
piece with the antepectus. ‘The part we are now con- 
sidering varies in different genera. Sometimes it is very 
narrow, as in Scarites; at others very broad, as in Bu- 
prestis, Nepa, &c. In the Lampyride, except Pygolam- 
pis*, it projects posteriorly into a lobe or tooth, which 
® Pirate VIII. Fic. 1. > Ibid--Fic. 2. a’. 
© bid. Fic. 1, 10. a. 4 Tbid. b. 
e Ibid. c. £ Ibid. 5. © Thid. a. 
5 We call by this name those Lampyride which have the head 
only partly covered by the prothorax, as L. ttalica, &c. 
