Phylacobiosis: see symbiosis.

Prosternal process: in aquatic Coleoptera a modification of the prosternum used in the differentiation of species.

Sub-clypeal pump: in some Diptera, the enlarged, more or less bulb- like structure at the anterior entrance of the oesophagus.

Sub-clypeal tube: in Diptera: see pharynx.

[EXPLANATION OF PLATES.]

[PLATE 1. Structures of the External Body Wall.]

1. Harpalus caliginosas showing the underside, and the head from above, to show the regions and the position of the sclerites.

2. Thorax of a Dipteron to show location of bristles.

3. Lateral view of a denuded Lepidopteron to show arrangement of sclerites.

4. Abdominal segment of a caterpillar to show the position of the tubercles.