CONTENTS OF VOLUME XX 
1. A Review of the Biology of Sex-determination. By Sidney I. Korn- 
hauser 1 
2. The Meander Patterns of Rios Secure and Mamore, Eastern Bolivia. 
By Kirtley F. Mather 22 
3. Primitive Musical Instruments of the Denison Collection. By Karl 
H. Eschman 28 
4. Notes on Medinan, Niagaran, and Chester Fossils. By Aug. F. 
Foerste 37 
5. The Egg and Larva of Hesperia juba Bdv. By A. W. Lindsey 121 
6. The Occultation of Venus by the Moon on January 13, 1923. By P. 
Biefeld : 127 
7. A Botanical Survey of the Campus of Denison University. By 
Dwight Munson Moore 131 
8. The Underground Migration of Oil and Gas. By Kirtley F. Mather.. 155 
9. Trichoptilus pygmaeus Wlsm. and the Neuration of the Family 
Pterophoridae. By A. W. Lindsey 187 
10. Notes on American Paleozoic Cephalopods. By Aug. F. Foerste 193 
11. A Report on the Theory of Relativity. (Einstein Theory). By P. 
Biefeld , 269 
12. Some Problems of Taxonomy. By A. W. Lindsey 289 
13. Notes on the Geology of Giles County, Virginia. By George D. 
Hubbard and Carey G. Croneis 307 
Subject and Author Index 379 
