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Show 1873.] COLOURING IN INSECTS. 157 colour in correspondence with the prevailing tint of its district, being light when from chalk, dark from peat, and reddish brown from clay. Similarly, Dr. Moller, in the paper before referred to, has recorded that Elaphrus riparius is of a brown colour when in sandy districts, but is green when in meadow-lands. The African Eremiaphila, described by M . Lefebvre *, furnishes an excellent example of the class now under consideration. This desert-insect is described as having perfect identity of colour with the ground on which it lives, and is stated to vary in colour from brown to silvery white, according to the colour of the soil on which it occurs. One remarkable case recorded by Dr. Wallace belongs perhaps to the present class. Referring to Bombyx cynthia, the author observest:-"The earliest bred specimens were of a predominant olive-green ground-colour, whereas the later bred, and especially those that escaped from pupae in September, not having passed a winter in cocoon, were of a predominant yellow tint. . . . Exceptions of course occur to this rule, but they are very few. It is hardly necessary to observe that these tints closely resembled the shades of the Ailanthus-leaflets, which assume a yellower tint as the season advances and the leaflets grow older." Although insects furnish the largest number of cases of " variable protective colouring," examples are not wanting in other classes of the animal kingdom. Thus among Crustacea the Chameleon Shrimp (Mysis chamceleon) has been so named from its power of changing colour according to the locality which it inhabits, being grey on sand, brown among seaweeds, and green when among Ulva and Zostera. It is well known that many species of fish, especially of the family Pleuronectidae, are capable of changing colour in correspondence with the colour of the bank on which they are resting or the water which they inhabit %. It is stated by Mr. Andrew Murray, also, that various birds are capable of undergoing a similar, though more permanent, alteration in colour §. Definition of variable protective colouring. The class of cases of which I have just given examples I propose to group together in a fifth class of the above-given classification, which, with this addition, is thus made to embrace all the known cases of protective resemblance. It will therefore become necessary to find a definition, as precise as the materials will permit, of the * Ann. Soc. Ent. de France, iv. p. 455. t Trans. Ent. Soc. vol. v. p. 485. t See for instance, Yarrell on the Flounder, Brit. Fishes, 2nd ed p 304; also Mr. Andrew Murray's paper on the " Disguises of Nature Edinburgh New Philos. Journ., Jan. 1860; and Prof. Cope on "The Method of Creation of Organic Forms," Proc. Amer. Philos. Soc. vol. xn. 1871, p. 2G0 M y friend the late Mr. J. K Lord, of the Brighton Aquarium, confirmed this statement with regard to the Pleuronectidee. ]D ,., ., - 8 Loc cit p 11 The species cited are the Grouse and Partridge : the lormer are stated to be very light brown in the low corn districts, so as to match the stubble; while the Moor-Partridges, which frequent the heather, are said to be darker than those of the lowlands. |