^14 Transactions. 



protective resemblance, but in the absence of adequate obser- 

 vation and experiment nothing definite can be said on the point 

 with regard to the present species. Some apterous females are 

 ■considered to mimic spiders, but, except in the case of immunity 

 from attack by other spiders, it is difficult to see in what manner 

 such mimicry would benefit them. 



Orthosia. 



Mr. Meyrick states that the members of this genus are almost 

 all autumnal, and that " their yellow and ferruginous colouring 

 is doubtless adapted to the autumn tints of falling leaves." 

 This is strikingly true of 0. immunis, but 0. comma appears in 

 November. Its variegated and speckled appearance Avould har- 

 monize well with the dead and decaying leaves which are to be 

 found in the bush at all seasons. 



Xanthia purpurea. 



This moth resembles in colour a much darker dead leaf than 

 Orthosia immunis imitates, and the greyish dots and strigae 

 resemble those minute patches of mould which are often found 

 on decaying leaves in damp situations. 



Leucania. 



It is difficult to see how the grey colouring of moderata 

 and its allies can be of value, but the ochreous and brownish 

 hues of atristriga, propria, unica, &c., bear considerable resem- 

 blance to faded leaves of grass, and as the larvae all feed on 

 GraminecB this must be of some importance to the perfect insect. 

 In some species, as in toroneura and neurce, the resemblance is 

 further enhanced by the veins being outlined in blackish ; in 

 others, as propria and acontistis, the same end is gained by 

 brownish or black basal and discal streaks. The light-yellow 

 forms, such as sulcana, semivittata, and others appear to be 

 rather conspicuous insects ; on dead, dry herbage, however, 

 they would be far from noticeable, and in this connection the 

 black dots which are scattered over the wings have probably 

 some use in assisting to render the resemblance still more 

 natural, dried herbage being often covered with such spots. 



Melanchra. 



The markings of the species of this genus are, as Meyrick 

 observes, " usually very similar, and the colouring dull and 

 adapted to conceal insects which are accustomed to hide amongst 

 dead leaves or refuse." Several forms, however, seem to have 

 a, tendency to rest on trees ; for instance, niutans is often found 



