118 ILLINOIS ACADEMY OF SCIENCE 



all others — and the average of the entire series showed 

 abont 87 per cent to have originated locally or at no great 

 distance. 



If I understand my colleague, Professor T. E. Savage, 

 correctly, his extensive studies of Champaign County do 

 not warrant a belief that the largest part of even the very 

 deep drift which covers central Illinois lias originated more 

 than fifty miles away from its present position. 



The University of Illinois, March, 1919. 



Explanation of Plates. 



139. Qucrcus ellipsoklalis. The tree from which type 

 collections were made. Photographed near Thornton by Mr. 

 C. F. Millspaugh in company with the author of the species. 

 Published by permission of the Field Museum of Natural 



History. 



140. Qncrcus ellipsoidaUs. Representative but rather 

 rough bark. Photograplied near Thornton by Dr. C. F. 

 Millspaugh. Published by permission of the Field Mu- 

 seum of Natural History. 



141. Qucrcus eUijisoidalis. Two of the many foliage 

 forms found in the type region of Cook Co., Illinois, about 

 one-third natural size. From specimens in the Hill herb- 

 arium at the University of Illinois. 



142. Qnercus ellipsoidaUs. Forms of fruit: natural size. 

 Upper row, the typical form. Second row, f. incurva. 

 Middle row. f. intermedia. Fourth row, f. depressa. Bot- 

 tom row, f. coronata. 



143. Above : buds of Quercus ellipsoidaUs, in the upper 

 row; Q. pahisfris in the center, Q. coccinea at tlie left, and 

 Q. velutina at the right, in the lower row. All enlarged 4 

 diameters. Below : Range of variability in the fruit of 

 Q. velutina, for comparison with the range in ellipsoidaUs 

 fruit. All of natural size. 



