( xcvii ) 



The cases of rantual agreement in aspect may be classified in two gronps — 

 similarity as the outcome of adaptation towards the same or similar extraneous 

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



Tlie colour and pattern of tlie upperside of the body and forewing of 

 Sphiiii/idue are very generally imitative of the bark of trees, variegated with 

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

 Beetles, Orthoptera, etc. The similarity is often enhanced by the ap|iearance 

 of i)rojections — as, for instance, the thoracical tufts of Krinni/is, I'sciidosphinx, 

 Hemeroplaiies nomius, Kpistor, and Notodont.idae. The silvery marks of tlie fore- 

 wing of Nephde, Hemeroplanes, Madortjx, etc., and, among Noctuidae, of Plusia, 

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

 subajiical huffish j)atch of Euri/pten/x molncca and some Notodonts has the 

 same efi'ect. 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 

 acquired almost everywhere. In Sphingidae a very irregular distal margin occurs, 

 commonly among Ambulicinae, Sesiinae, and Philampeliiiae. In Acheroiitiinae 

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

 ClioerocaiiipiiHie which has an irregularly lobed forewing looking like a piece 

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

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

 have a dark apical line indicating the midrib {Clanis, some Polypti/chus), or it 

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

 like entire forewing among Sphingidae, 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 Gastropacha (juercifolia, in which 

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

 found in some Amhulicinae, Sesiinae, and Philampelinae — namely, in Amorpka, 

 Calasjjmbolm, Phi/llosphingia, Stolidoptera, and Hgpaedalia, perhaps also in 

 llegmapleru. 



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

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

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

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

 fasciata and the mimetic Huemorrhngia dijfinis is purely adventitious, both 

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

 other. 



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

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

 the similarity has independently arisen, insects similar to each other iu this way 

 may occur in widely sej)arated countries. 



Thongli very many Sphinqidae are similar to one another, there does not 

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

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



9 



