It has also to seek for a place to lay its eggs. Wings would keep it 

 on the outside of the thick bushes and hedges it frequents, but the 

 absence of wings and its well-developed legs enable it to crawl 

 rapidly over the twigs of its food-plant in search of a suitable twig on 

 which to lay its eggs, and to hide during the daytime in such corners 

 and crevices as the trees and bushes afford. Males of Diurnoea fagella 

 appear to have but little protection beyond that which their colour 

 give them in connection with the resting place they choose. The female 

 again with its large body, would with wings be still more conspicuous. 

 But the female rarely appears to emerge before dark, and then 

 crawls rapidly up the tree-trunks where the males are resting and 

 copulation then takes place. By the morning the females are gone, 

 probably to the upper branches where they hide and lay their eggs, 

 and are rarely seen again, the more conspicuous males remaining still 

 on the trunk below. The habits of Psyche are essentially different. 

 Protected by their cases as larvas, the males on emergence fly rapidly 

 in the sunshine, and fall down into the grass or herbage when dis- 

 turbed or when the sunshine fails, and in this way receive some 

 measure of protection. The females, on the other hand, are but little 

 different to the larva? and remain in their cases. The males are pro- 

 vided with strongly pectinated antenna? to enable them to find the 

 females, but their time of flight, and I believe the period of their 

 existence is very limited, and it happens that the females are able, 

 without copulation, to lay large numbers of fertile eggs and to produce 

 parthenogenetically, vast numbers of offspring, although it is assumed, 

 and I believe rightly, that males are never produced from the par- 

 thenogenetic ova and larva?. It may, of course, be urged that in a 

 state of nature under this arrangement, the $ must inevitably become 

 extinct in a few generations, and in some species they may probably 

 have almost done so. But there appears no reason to suppose but 

 that parthenogenetically-derived females may be fertilised by a male 

 so as to produce a further supply of males and the production of a 

 very few males per year would necessarily be sufficient to keep that 

 sex from becoming positively extinct. It is remarkable that in most 

 species of Psyche and their allies, however, that a large proportion of 

 cases give nothing but females, an occasional male being all that one 

 usually breeds out of a very large number. Here then is a class dis- 

 tinct in itself, and differing from Orgyia on the one hand, and Hybernia, 

 Nyssia and Diurnoea on the other ; but the analogy between Psyche ' 

 and its allies and Orgyia is much stronger than between either of 

 these and the other genera just mentioned. The analogy between 

 Ni/ssia, Hybernia, Diurnoea etc., is, however, very close indeed. To 

 sum up then. It is the character of Orgyia to spread itself about by 

 wandering in search of a place to pupate in. It has also found out 

 that the eggs passed the winter more safely and were better pro- 

 tected by being laid on the cocoon or web, the web keeping them 

 away from wet surfaces &c. The eggs, also, are largely protected by 

 their hard shell, although they are severely attacked by a minute 

 hymenopterous parasite. The necessity that the genera should lay a 

 large number of eggs is, therefore, self-evident. The female had no 

 actual use for wings and they gradually atrophied, possibly because 

 they had not only become useless, but would actually serve to attract 



