DESCRIPTION OF PLATE I. 



Embryology op Aphis. 



Fig. 1. — Unborn foetus of Aphis pruni. The limbs 

 have been disengaged from the folded mass by needles. 



Fig. 2. — Another specimen, which has not been so 

 unfolded : c c, of both figures, represent the cephalic 

 lobes. 



Fig. 3. — Unborn embryo from the pseudovarium of 

 Lachnus viminalis : c, head ; g, the rudiment of the 

 pseudovaria, below which may be traced the antenna?, 

 the legs, and the elements of the rostrum. 



Fig. 4. — Another and less-matured embryo. Both 

 these forms are invested in the membranes afterwards 

 to be thrown off at birth, c and g represent the same 

 organs as before. 



Fig. 5. — Unborn foetus of Pemphigus lactucarius. 

 These embryos have been toughened by soaking in 

 dilute alcohol, a, antenna ; r, rostrum ; I, legs. 



Fig. 6. — Another example, drawn when nearly ready 

 for birth. Similar parts may be distinguished as seen 

 in the former examples : I, legs ; r, rostrum. 



Fig. 7. — Embryo of the same species, which would 

 have furnished the pupal, and finally, the alate form. 

 In this unborn condition the rudiments of wing-cases 

 may be traced. Conditions analogous to the caterpillar 

 are thus fulfilled on the foetus within the body of the 

 parent, w, wing case. 



Fig. 8. — Embryo of Pemphigus, just born, showing 

 that the antenna? (d), which are very simple in articu- 

 lation, are disengaged before the other limbs. 



Fig. 9. — A much-magnified front view of one of the 

 late broods of Pemphigus lactucwius. a, antenna ; r, 

 rostrum ; I, legs. 



These examples are figured to exhibit the very 

 diverse forms of the embryos of different genera and 

 even broods of Aphis. Perhaps they may be suggestive 

 of primaeval types and represent an ancient ancestry. 



Fig. 10. — Embryo extracted from the pedunculated 



