Miscellaneous. 151 



When we examine with the naked eye or with a lens the embryos 

 of the brown Aphis of the maple at the moment of their being pro- 

 duced by the females, or after opening the bodies of the latter, we 

 see at once that all of them have not the same coloration. In some 

 they are of a tolerably bright green, whilst in others their colour is 

 more or less brownish or greenish brown. The brown embryos pre- 

 sent no peculiarities, and only differ from their mothers by characters 

 analogous to those which are remarked in all species of Aphides 

 between the newly born young individuals and the adult females. 

 As in these latter, their bodies and appendages are furnished with 

 rather long simple hairs, and, like all young Aphides at the moment 

 of their birth, they already contain rudiments of embryos in the 

 interior of their generative apparatus. If, on the other hand, we 

 examine the green embryos, we at once detect, besides their peculiar 

 coloration, very marked diiferences between them and their brown 

 congeners. The various parts of the body and limbs do not present 

 the same conformation as in the latter, but one is especially struck 

 by the extraordinary development and the unusual appearance of 

 their tegumentary system. Thus their surface is no longer furnished 

 only with simple hairs, but also and principally with scaly transpa- 

 rent lamellae, more or less rounded or oblong, and traversed by 

 divergent and ramified nervures. These lamellae occupy especially 

 the anterior margin of the head, the first joint of the antennae (which 

 is very stout and protuberant), the outer edge of the tibiae of the two 

 anterior pairs of legs, and the lateral and posterior margins of the 

 abdomen. Moreover the whole dorsal surface of the latter and of 

 the last thoracic segment is covered with a design having the aspect 

 of a mosaic composed of hexagonal compartments, and which is 

 not without analogy to the pattern formed by the scaly plates of 

 the carapace of tortoises. These peculiarities give our insect a great 

 elegance of appearance, which causes it to be much in request with 

 the amateurs of the microscope in England, where it is commonly 

 known under the name of the "leaf-insect." The entire animal is 

 strongly flattened, and resembles a small scale applied to the surface 

 of the leaf upon which it reposes, and on which it requires a certain 

 amount of care to detect it. 



Another remarkable character of these abnormal individuals of 

 Aphis aceris is the rudimentary state of their generative apparatus. 

 This is reduced to a few groups of small pale and scarcely visible 

 cells, none of which arrives at maturity to become transformed into 

 an embryo ; and it retains this character as long as it is possible to 

 observe the animal. The functions of nutrition, also, are performed 

 in them in a very unenergetic manner; for from the moment of their 

 birth until that at which we cease to observe them, they increase 

 but little in size, attaining scarcely 1 millimetre. They undergo no 

 change of skin, never acquire wings like the reproductive individuals, 

 and their antennae always retain the five joints which they present 

 in all young Aphides before the first moult. Nevertheless they 

 possess a well-developed rostrum and an intestinal canal, the peri- 



