130 BRITISH APHIDES. 



also a circulation may be detected in all the legs. 

 Globules pass slowly, and by a fitful motion, down the 

 inferior and up the superior portions of the tibiae. 

 Life seems very tenacious in the legs, for these move- 

 ments may be watched for a considerable time after 

 the insect has been dismembered and placed under 

 weak syrup. 



A still more remarkable fact relates to the extremely 

 rudimentary character of the generative organs. This 

 apparatus is reduced to a few inconspicuous cells, 

 which at the end of the insect's life do not appear to 

 have undergone any alteration or approach to ma- 

 turity. This is singular, for this dimorph prolongs its 

 existence apparently for four months or more, during 

 which it never leaves the leaf on which it was born. 



The antennsD do not pass out of their rudimentary 

 form with five obscure articulations, and no approxi- 

 mation is made towards the development of nectaries. 



Balbiani and Signoret affirm that the insect neither 

 moults its integuments, nor assumes wings. I have, 

 however, clear proof that the skin is occasionally shed, 

 and I possess casts complete even to the folioles or 

 flabellge. Moreover, I have every reason to believe 

 that when such moults occur, the insect emerges with- 

 out folioles, such organs being replaced by tufts 

 of hair. I am therefore inclined to think that these 

 flabellae have some reference to these bristles, and that 

 possibly they may be regarded as kinds of developing 

 capillary sacs.* 



Should this prove true, the bristles and capitate 

 tufts of insects will show but little analogy with the 

 hairy coverings of vertebrates, the growth of which 

 proceeds from sacs deeply seated in the skin of the 

 animal. 



In Plate LXXIX, fig. 8, I have figured an insect 

 which was found so close to the slough, (also figured), 



* An examination of tlie hair on the tubercles of the yonng of 

 Chaitrq^horus aceris does not, however, show any numerical relation to 

 the radiat'-ug vessels contained in the follicles of the i.seudomorph. 



