The Hydriomenidae are thus characterized:—
"Tongue well developed. Fore-wings with vein 10 rising separate; anastomosing with 11 and 9 (forming double areole), or rising out of 11 and anastomosing with 9 (forming simple areole). Hind-wings with vein 5 fully developed, parallel to 4, 6, and 7 almost always stalked or connate, 8 anastomosing with upper margin of cell from near base to beyond middle, or sometimes approximated only and connected by a bar or shortly anastomosing beyond middle." (Plate [II]., figs. 19 to 43.)
"A very large family distributed in equal plenty throughout all temperate regions, but becoming scarcer within the tropics. The structure is very uniform throughout, and the generic distinctions slight. Imago with body slender, fore-wings usually broad.
"Ovum broad, oval, rather flattened with usually oval reticulations. Larva elongate, slender, with few hairs, without prolegs on segments 7 to 9; often imitating live or dead twigs and shoots. Pupa usually subterranean."—(Meyrick.)
This family is very extensively represented in New Zealand by the following fifteen genera:—
| 1. [Tatosoma]. | 5. [Elvia]. | 09. [Venusia]. | 13. [Dasyuris]. |
| 2. [Paradetis]. | 6. [Hydriomena]. | 10. [Asaphodes]. | 14. [Notoreas]. |
| 3. [Chloroclystis]. | 7. [Euchœca]. | 11. [Xanthorhoe]. | 15. [Samana]. |
| 4. [Phrixogonus]. | 8. [Asthena]. | 12. [Lythria]. |
| 1. [Tatosoma]. | 09. [Venusia]. |
| 2. [Paradetis]. | 10. [Asaphodes]. |
| 3. [Chloroclystis]. | 11. [Xanthorhoe]. |
| 4. [Phrixogonus]. | 12. [Lythria]. |
| 5. [Elvia]. | 13. [Dasyuris]. |
| 6. [Hydriomena]. | 14. [Notoreas]. |
| 7. [Euchœca]. | 15. [Samana]. |
| 8. [Asthena]. |
Genus 1.—TATOSOMA, Butl.
"Face smooth. Palpi long, straight, porrected, shortly rough-scaled, terminal joint short. Antennæ in male simple, stout, gradually dilated from base to near apex, apex attenuated. Abdomen in male very excessively elongate. Hind-wings in male deeply excised near dorsum, dorsal lobe folded into a long pocket, fringed with hairs. Fore-wings with vein 6 rising out of 9, 7 from or above angle of areole, 10 anastomosing moderately with 9, 11 anastomosing moderately with 10, 12 free. Hind-wings with veins 6 and 7 separate, 8 free, united with 7 before transverse vein by an oblique bar.
"This singular genus is a remnant of a widely diffused, but now fragmentary group, to which belong also Lobophora (Europe), Rhopalodes (South America), Sauris (Ceylon), and Remodes (Borneo.) In all, the hind-wings of the male are peculiarly modified, usually much diminished in size, and with the dorsum formed into a distinct lobe, the object of which is unknown. A similar structure is found only in one or two genera of Tortricina. Rhopalodes is the nearest genus to this, but vein 5 is said to be obsolete, and the lobe does not form a pocket; in Sauris the areole is simple, and the antennæ thickly scaled; in Remodes the areole is also simple, the antennæ flattened and scaled, and the dorsum is furnished with three superposed lobular folds, so that it represents the extreme of development in this direction."—(Meyrick.)