( xcvii ) 



Th(! Otif^es of miitiuil agrociuent in asipect may lie classified in two groups — 

 similarity as tlie outcome of adajitation towards the same or similar extraneous 

 objects, and similarity as the jimduct of adaptation to each other. 



The colour and ])attern of tlie upperside of tlie body and forowinL;" of 

 Sphinqiihie are very generally imitative of the bark of trees, variegated witli 

 algae and lichens. The bark-jnittern is common to a great many Moths, 

 Beetles, Ortho]itera, etc. The similarity is often eniianced b\' the appearance 

 of projections — as, for instance, the thoracical tufts of Eriniii/is. I'seudosjthinx, 

 Hetneroplanes nomn/s, Kj/it^tor, and Notodordichte. The silvery marks of the fore- 

 wing of Xepht'le, Hemeroplanes, Madori/x, etc., and, among JS^octuidae, of IHusia, 

 break the uniformity of the wing, as do white lichens that of the bark. The 

 subapical butttsh jiatch of Eiiri/pteri/x niohwca aud some Notodonts has the 

 same effect. The shape of the distal margin conforms very often to the irregu- 

 larity of the bark. A dentate, scalloped, or lobate distal margin may be 

 actpiired almost everywhere. In Spliingidae a very irregular distal margin occurs, 

 commonly among Amhulicinae, Sesiinae, and Fhilampelinae. In Acheroiitiinae 

 the margin is at the highest undulate, while there is one (American) species of 

 Choerocampinae which has an irregularly lobed forewing looking like a piece 

 of wood {Phanod-'/la). A resemblance to leaves is also frequently met with, 

 especially among Amhulicinae. The leaf-like forewing may either be entire and 

 have a dark apical line indicating the midrib (<7««/.5, some Poli/pfi/cluis), or it 

 may be irregularly lobed. Phi/lloxiphia (PI. I. f. 4) has perhaps the most leaf- 

 like entire forewing among Spliingidae, the midrib being here represented by a 

 line running from the apex to near the base. The clayish colour of this insect, 

 agreeing with the colour of dry leaves, occurs abundantly in Hawk Moths. A 

 leaf-imitation after the well-known pattern of GaHtroparha quereifolia, in which 

 the widened hindwing projects beyond the costal margin of the forewing, is 

 found in some Amhulicinae, Sesiinae, and Pliilampelinae — namely, in Amorpha, 

 Calasi/mholus, Plii/llosphingin, StoUdoptera, and Ihjpaedalia, perhaps also in 

 Dcgmapiera. 



Besides the imitations of leaves, bark, and other non-animal subjects, 

 there are striking cases of resemblance to other insects among the Spkingidae. 

 The imitation of humble-bees and humming-birds by some Sesiinae is well 

 known. And here again similarity between the mimetic Euproserpiniis flavo- 

 fasciata and the mimetic Haemorrhagia diffinis is purely adventitious, both 

 imitating the same or similar models, and therefore resembling also each 

 other. 



The resemblance of two species to each other acquired indirectly in the 

 way indicated is of frequent occurrence. And it is easy to perceive that, since 

 the similarity iias independently arisen, insects similar to each other in this way 

 may occur in widely separated countries. 



Though very many Sjikingidae are similar to one another, there does not 

 seem to be a species which mimics another Sphingid — i.e. of which tiie pattern 

 or shape has been developed directly in relation to the other, 



