iosis: see symbiosis.

Heliophobic: loving darkness: applied to species that shun the light,
like, e.g. Termites.

Heliotactic: light loving: applied to species that live in the open and in
daylight.

Lestobiosis: see symbiosis.

Meron: in Neuroptera, a sclerite posterior to the coxa and below the
epimeron: corresponds to the trochantine in Lepidoptera.

Metasternal wing: in some aquatic Coleoptera a leaf-like expansion
above the coxal plates.

Myrmecophily: is the relation existing between ants and those guests
that seek their company primarily for their own individual advantage.

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.

5. Lateral view of a dragon fly to show the body sclerites.

All the abbreviations used in this plate are readily understood.

PLATE II. Structures of Head, Mouth, Thorax & Genitalia

1. Head of wasp from front.

2. Head of honey bee with mouth parts extended.

3. Head of Locustid from front, to show regions.

4. Head of a Lepidopteron from front.

5. Head of a cricket from front.

6. Labium of a cricket showing all usual parts.

7. Maxilla of Harpalus caliginosus, with all sclerites marked.

8. Mandible of Copris carolina with all sclerites defined.

9. Thorax of a Hymenopteron from above.

10. Genitalia of a male mosquito with all parts named.

11. Genitalia of a male Noctuid from below: the parts separated out.

PLATE III. Venation According to the Comstock System.

1. Wing venation of a Noctuid.

2. Wing venation of a Hepialid.

3. Wing venation of a Locustid.

4. Wing venation of a Hymenopteron.

5. Wing venation of a Dipteron.

6. Wing venation of an Odonat.

7. Wing venation of a Cicada.

Abbreviations are as follows:

C. Costa, except