TRACHEATA 
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mouth and anus. The mouth is overhung by the labrum, and 
has the mandibles and first maxillae on either side; behind 
it is bounded by the labium or fused second maxillae; the 
mandibles cut and crush the food, which is held in position 
by the maxillae. The passage of the food into the mouth is 
assisted by a hairy prominence on the anterior surface of the 
labium. 
The mouth leads into an oesophagus which pierces the 
nerve mass, and then swells into an inconspicuous crop; this 
Fic. 187.—View of male Melolontha vulgaris, 
from which the dorsal integument and heart 
have been removed to show the internal 
organs. After Vogt and Yung. 
1. Cerebral ganglion. 10. Malpighian tubules, brown portion, 
2, 1st thoracic ganglion. with caeca. 
3. 2nd and 3rd thoracic ganglion. 11. Malpighian tubules, distal end. 
4. Fused abdominal ganglia. 12. Tracheae with vesicles. 
5. Oesophagus. 3. Testes, opening into coiled vasa 
6. Mid-gut. deferentia. 
7. Small intestine. 14. Penis. 
8. Colon. 15. Single vas deferens. 
9. Rectum. 
opens into a brown mid-gut, in which the processes of diges- 
tion are mainly carried on. The mid-gut passes into a finer 
tube, the small intestine, which receives the Malpighian tubules, 
and this in its turn passes into the colon, which has on its 
inner side six longitudinal muscular ridges; this opens through 
the rectum to the exterior. With the exception of the mid- 
gut, the alimentary canal is lined with a thin layer of chitin, 
continuous at the mouth and anus with the exoskeleton, and 
this is cast at the ecdysis of the exoskeleton. In Melolontha 
neither salivary glands nor hepatic diverticula are described. 
The Malpighian tubules are four in number; they are very 
