This is a very extensive group of the Lepidoptera, and so far as it is represented in New Zealand is equivalent to that group formerly known as the _Geometrina_, with the addition of the family _Sphingidæ_. The insects here included comprise many of our most interesting, abundant, and beautiful species. Some of them are so extremely variable that it is often a matter of considerable difficulty to determine the most convenient points on which to base the specific distinctions; although fortunately great advances have been made in this direction of late years owing to the increase in the number of workers, and the consequent accumulation of available material. In connection with this portion of the subject, special mention should be made of Mr. Meyrick's paper on the group, which appeared in the 'Transactions' of the New Zealand Institute for 1883. This essay has been of the greatest value in dispelling the doubts which formerly existed respecting the limits of many of the most variable species. The _Notodontina_ are represented in New Zealand by the six following families:-- 1. HYDRIOMENIDÆ. 4. ORTHOSTIXIDÆ. 2. STERRHIDÆ. 5. SELIDOSEMIDÆ. 3. MONOCTENIADÆ. 6. SPHINGIDÆ. Family 1.--HYDRIOMENIDÆ. 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.) {39}This family is very extensively represented in New Zealand by the following fifteen genera:-- 1. TATOSOMA. 5. ELVIA. 9. VENUSIA. 13. DASYURIS. 2. PARADETIS. 6. HYDRIOMENA. 10. ASAPHODES. 14. NOTOREAS. 3. CHLOROCLYSTIS. 7. EUCHOECA. 11. XANTHORHOE. 15. SAMANA. 4. PHRIXOGONUS. 8. ASTHENA. 12. LYTHRIA. Genus 1.--TATOSOMA, Butl.