VOLUME 55. 



1, Robinson, B. L. — I. On tropical American 'ComposiUio, chiefly Eupatorisae. II. A. 



Recension of the Eupatoriums of Peru. pp. 1-8S November. 1919. $1.25. 



2, RiTTKR, Wm. E. — A Step Forward in the Methodology of Natural Science (an 



Introduction to: The Functional Relation of one Variable to each of a Number of 

 correlated Variables determined by a Method of Successive Approximation to Group 

 Averages. By George F. McEwen and Ellis L. Michael.) pp. 89-133. December, 

 1919. . $1.50. 

 .3. LoTK.\. Alfred J. — Contribution to the General Kinetics of Material Transfor- 

 mations, pp. 135-153. March, 1920. $.65. 



4. Phillips, H. B. and Moore, C. L. E. — Rotations in Space of Even Dimensions. 



pp. 155-lSS. March, 1920. $.85. 



5. SE.VRLE, Arthitr. — Orbits resulting from Assumed Laws of Motion. pp. 189-207. 



May. 1920. 65c. 



6. Th.axteb, Roland. — New Dimorphomyceteae. pp. 209-282. May, 1920. $.85. 



7. LiPKA, Joseph. — Some Geometric Investigations on the General Problem of 



Dynamics, pp. 283-322. June, 1920. 90c. 



8. Babgock, H. A.— Specific Heat of Ammonia, pp. 323-409. October, 1920. $1.35. 



9. Boulenger, G. a. — A Monograph of the American Frogs of the Genus Rana. pp. 



411-480. August, 1920. $1.25. 



10. Records of Meetings; Officers and Committees; List of Fellows and Foreign Honorary 



Members; Statutes and Standing Votes, etc. November, 1920. S.75 



(Continued on jiage 2 of cover.) 



