536 EXTERNAL ANATOMY OF INSECTS. 



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 shield, or upper part % and the ora, or under 

 part b . In the shield you are to observe its apex c , base d , 

 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 is a 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 Cara- 

 bus L. ; and in others merely by an impressed line, as in 

 Blaps F. ; but in Curculio and Cerambyx L., &c. there is 

 no ora, the shield being without a lateral margin, and 

 forming one piece with the antepectus. The part we are 

 now considering varies in different genera. Sometimes 

 it is very narrow, as in Scarites ,• at others very broad, as 

 in Buprestis, Nepa, &c. In Lampyris, except L. italica, 

 and affinities, it projects posteriorly into a lobe or tooth, 

 which forms a right angle with the rest of the ora, and 

 becomes the lower part of the cavity that receives the 

 head ; and in JDermestes this part is excavated into an 

 anterior and posterior one which admits the antennas and 

 arms when folded for repose. 



2. The margin of the prothorax is a ridge, either de- 



* Plate VIII. Fig. 1. * Ibid. Fig. 2. a. 



Ibid. Fig. 1, 10. a. «i Ibid. b. 



e Ibid. c. f Ibid. b. s Ibid, a, 



