PREFACE. Vll 



from Mr. Samuel Scudder's numerous published papers 

 on Fossil Insects; particularly from those sections 

 bearing on the fossil Aphides found in the beds of the 

 Florissant basin of Colorado. This gentleman has 

 most liberally allowed me to draw from some of his 

 plates which have not yet been published. Although 

 these forms are American, they have characters almost 

 identical with our recent European genera. 



To these sections I have also added a short account 

 of some of the Aphides which have been included in 

 masses of amber. 



The author trusts that the preliminary remarks of 

 this and the preceding volumes will be a sufficient 

 acknowledgment of the sources from which much of 

 his information has been drawn. 



Towards the close of this volume I have thrown 

 together some of the principal known facts relating to 

 the reproduction and embryology of Aphis ; and by way 

 of introducing this subject, I have attempted a sketch 

 bearing on the general growth of the ovum of insects. 

 I wish here to acknowledge my indebtedness to the 

 works of Dr. Allen Thomson, Professors Huxley, 

 Forster, and Balfour, Ray Lankester, Ernst Haeckel, 

 Dr. A. Brandt, E. Balbiani, and others. The late 

 Prof. Balfour's recent treatise on ' Comparative 

 Embryology ' is a mine of wealth to all biologists. 



In my former volumes I expressed, as strongly as I 

 was able, my obligations to many friends ; and I will 

 not here repeat my thanks. One gratification in the 

 study and illustration of natural phenomena is a con- 

 tinual growth of genial correspondence with those of 

 kindred thoughts and tastes. 



I must here, specially offer my thanks to Prof. 



