0HA.ITOPH0RUS ACERIS. 123 



that of Coccus, is capable of fecundating many suc- 

 cessive females, and, in accommodation with such 

 roving habits, in by far the larger number of instances 

 we find him provided with long effective wings suitable 

 for locomotion, and well-developed 63^68 and stemmata 

 to direct him to the objects of his solicitude. Such 

 being the case it is difficult to discover the special 

 economy of a far less developed form of the same sex 

 in which the same organs for transport, &c., are entirely 

 wanting ; and consequently these forms (which are 

 generally verydiminutive) must live and die^ it may be 

 said, on the leaves or places of their birth. The fact 

 of this double form cannot be doubted, and indeed we 

 have already considered both apterous and winged 

 males in some foregoing species, although they have 

 not appeared conjointly and supplementary. 



It is refreshing to notice the fidelity and strictness 

 to fact often shown by the veteran pioneers of science. 

 It cannot be said that they were wanting in imagina- 

 tion in philosophy — a good quality if kept under due 

 control, yet it is marvellous how much they made out 

 with their comparatively inefficient instrumental means. 



De Greer has given us a rough figure of the apterous 

 male of the sycamore Aphis, and also a characteristic 

 one of the apple Aphis. 



I am indebted to the kindness of Monsieur J. Lich- 

 tenstein for examples of both these male forms, and 

 also for specimens of the viviparous female, concealed 

 in her woody winter nidus amidst her deposited eggs. 

 To him I am indebted for the fact that winged and 

 unwinged males simultaneously occur in Ghaitophorus 

 aceris. In a letter dated Oct. 29th, 1877, he writes : 



" Two days ago I searched my Acer Mo7ispelliensis, 

 and I found winged and unwinged insects of both 

 male and female sexes ; the male is black or brown, 

 with a well-formed penis, and the antennae yg- longer 

 than those of the female. This male answers to Koch's 

 Plate III, fig. 19. The female is yellowish-white, and 

 has the usual brown markings. But, mixed with them, 



