82 ILLINOIS BIOLOGICAL MONOGRAPHS [324 



(16) The significance of the adfrontal suture has been determined upon 

 the basis of postembryological evidence. This suture is a modification 

 functioning as a means of ecdysis at the time of pupation. 



(17) Sensory hypodermis, such as that of the ocellarae and sensoria, 

 does not grow as rapidly as the ordinary hypodermis. 



POSTSCRIPT 



Much of the data of this investigation is included in twelve statistical 

 tables which were submitted with the manuscript. The intricacy of these 

 tables is such that it has been impossible to reproduce them here. They 

 were included in the original copy of the thesis which is deposited in the 

 Library of the University of Illinois, where they can be consulted by those 

 interested. 



ACKNOWLEDGMENTS 



Chief among those to whom the author wishes to express his indebted- 

 ness for their aid and encouragement during the progress of this investiga- 

 tion is Dr. A. D. MacGillivray. The value of his constant advice and 

 suggestions, the fruition of a life-time study of the morphology of insects, 

 could hardly be over-expressed. His kindly interest has been a continued 

 source of encouragement. The terms employed in his forthcoming "Exter- 

 nal Insect-Anatomy" have been generously placed at the author's disposal, 

 so that much circumlocution and coining of new terms has been avoided. 



To Dr. S. A. Forbes the author wishes to express his sincere thanks for 

 the use of the collection of the Illinois State Laboratory of Natural History. 

 Since it has been necessary that practically all other material be collected 

 and reared, the some thirty-five species of noctuid larvae in the collection 

 were indispensible for the comparative morphological part of this work. 

 Dr. C. P. Alexander and Mr. J. R. Malloch of the State Laboratory have 

 extended numerous courtesies, which have aided very materially in the 

 progress of these investigations and which are sincerely appreciated. 



For their general aid and encouragement the author is greatly indebted 

 to Drs. V. E. Shelford, J. W. Folsom, R. D. Glasgow, and H. Yuasa. 

 Certain of the experiments recorded above could not have been performed 

 except by the use of the constant-temperature chambers in the Vivarium 

 Building which were provided by funds from the Graduate School. 



