CONTENTS. 



PART No. 82, APRIL 1918. 

 Papers. 



PAGE 



A. B. Rendle, M.A., D.Sc, F.R.S. The President's Address : 

 The Use of Microscopical Characters in the Systematic 

 Study of the Higher Plants . . . . . .353 



'G. T. Harris. On Schisfostega osmitndacea Mohr. (Plates 23 



and 24, and Figs. 1-3 in text) . . . . .361 



W. Williamson, F.L.S., F.R.S. E., and Charles D. Soar, F.L.S., 



F.R.M.S. Lebertia sejveiV^&XiQv. (Plate 25). . . 375 



Notes. 



Edward M. Nelson, F.R.M.S. On the Measurement of Magni- 

 fying Power ........ 379 



Edward M. Nelson, F.R.M.S. Carl Dietrich Ahrens . .381 



Prof. Frederic J. Cheshire, C.B.E. Carl Dietrich Ahrens . 383 



Proceedings, etc. 



Proceedings from October 23rd, 1917, to March 12th, 1918, 



inclusive ......... 385 



Fifty-second Annual Report (1917) ...... 399 



Treasurer's Report (1917) ....... 405 



Table for the Conversion of English Metrical Linear Measures . 406 



PART No. 83, NOVEMBER 1918. 



Papers. 

 Sir Nicholas Yermoloff, K.C.B., K.C.V.O., F.R.M.S. Notes 



on some Intermediate Forms of the Genera Navicula and 



Cymbella. (Plates 26-28) 407 



Prof. G. S. West, M.A., D.Sc, F.L.S. A Further Contribution 



to our Knowledge of the Two African Species ot Volvox. 



(Plates 29 and 30) 425 



Edward M. Nelson, F.R.M.S. The Binocular Microscope . 429 



Notes. 



Edward M. Nelson, F.R.M.S. Microscope Eye-pieces . . 437 



Edward M. Nelson, F.R.M.S. Oil-immersion Dark-ground 



Illuminator (Fig. in text) ...... 438 



Proceedings, etc. 



Proceedings from April 9th, 1918, to June 11th, 1918, inclusive . 439 

 Index to Vol. XIII 449 



