CONTENTS. 



Transactions op thk Society — page 



I. — On (Ecistes umhella and other Rotifers. By 0. T. Hudson. 



M.A., LL.D., V.P.R.M.S. (Plates I. and II.) ., .. No. 1 1 



II. — A Further Inquiry into the Limits of Microscopic Vision 

 and the delusive application of Fraunhofer's Optical 

 Law of Vision. No. II. By Dr. Eoyston-Pigott, M.A., 



F.E.S.,&c. (Plate III.) „ 9 



III. — On some Recent Forms of Camera Lucida. By Frank 



Crisp, LL.B., B.A., Sec. E.M.S., &c. (5 figs.) .... „ 21 



rV. — Description of a New Form of Camera Lucida. By J. 



Cunningham Russell, M.D., Lancaster. (2 figs.) . . „ 25 



v.— Immersion Illuminators. By J. Mayall, jim., F.R.M.S. „ 27 



VI. — Note on a Revolver Immersion Prism for Sub-stage Illu- 

 mination. By James Edmunds, M.D., M.R.C.P. Lend., 



F.R.M.S., &c „ 32 



VII. — A Catoptric Immersion Illuminator. By John Ware 



Stephenson, F.R.A.S., Treas. R.M.S. (1 fig.) .... „ 36 



. VIII.— The Thallus of the Diatomacese. By F. Kitten, Hon. 



F.R.M.S „ 38 



IX.— The President's Address. By H. J. Slack, F.G.S. .. No. 2 113 

 X. — Observations on Dactylocalyx ptuniceus (Stutchbury), with 

 a Description of a New Variety, Dactylocalyx Stutchbury i. 

 By W. J. Sollas, M.A., F.G.S., &c. (Plates V.-VIII. 



and 4 figs.) „ 122 



XL— The Aperture Question. By J. Mayall, jun., F.R.M.S. „ 134 

 XII. — A Contribution to the Knowledge of British Oribatidae. 

 By A. D. Michael, F.R.M.S., with the assistance of 

 C. F. George, M.R.C.S.E. (of Kirton Lindsay). (Plates 



IX.-XI.) No.3 22.5 



XIII. — Notes on the Pygidia and Cerci of Insects. By Henry 



Davis, F.R.M.S „ 2.52 



XIV. — On Stephenson's System of Homogeneous Immersion 

 for Microscope Objectives. By Professor E. Abbe, of 



Jena, Hon. F.R.M.S „ 256 



XV. — The Vertical Illuminator and Homogeneous Immersion 

 Objectives. By J. "W. Stephenson, F.R.A.S., Treas. 



R.M.S. „ 266 



XVI. — Note on Diagrams (Plate XII.) exhibiting the Path of a 

 Ray through Tolles' a Immersion Objective. By Pro- 

 fessor R. Kdth „ 269 



VOL. II. 6 



