CONTENTS. VII 



PAGR 



XX. Report on the Pennatulida dredged by H. M.S. "Porcupine." By 

 A. Milnes Marshall, M.D., D.Sc, M.A., F.R.S., Beyer 

 Professor of Zoology in the Owens College ; and G. H. 

 Fowler, B.A., Ph.D., Berkeley Fellow of the Owens College, 

 Manchester. Communicated by John Murray, Esq. (Plates 

 XXXI., XXXIL), ...... 453 



XXI. On the Determination of the Curve, on one of the Coordinate Planes, 

 which forms the Outer Limit of the Positions of the Point of 

 Contact of an Ellipsoid which always touches the three Planes of 

 Reference. By G. Plarr, Docteur es-sciences. Communi- 

 cated by Professor Tait, ..... 465 



XXII. On the Partition of Energy between the Translatory and Rotational 

 Motions of a Set of Non-Homogeneous Elastic Spheres. By 

 Professor W. Burnslde, . . . . .501 



XXIII. A Contribution to our Knowledge of the Physical Properties of 



Methyl-Alcohol. By W. Dittmar, F.RSS. Lond. & Edin., 



and Charles A. Fawsitt. (Plate XXXIII. ), . . 509 



XXIV. On the Thermal Conductivity of Iron, Copper, and German Silver. 



By A. Crichton Mitchell, Esq. Communicated, with an 

 Introduction, by Professor Tait, Sec. R.S.E. (Plates 

 XXXIV., XXXV.), 535 



XXV. Critical Experiments on the Chloroplatinate Method for the De- 

 termination of Potassium, Rubidium, and Ammonium ; and a 

 Redetermination of the A tomic Weight of Platinum. By W. 

 Dittmar, F.R.S.E., and John M'Arthur, F.RS.E., . 561 



PART III. (1887-88.) 



XXVI. The Polychaeta Sedentaria of the Firth of Forth. By J. T. 

 Cunningham, B.A., Fellow of University College, Oxford, 

 F.RS.E., Superintendent of the Granton Marine Laboratory; 

 and G. A. Ramage, Vans Dunlop Scholar in Edinburgh Uni- 

 versity. (Plates XXXVI. -XL VII.), . . . 635 



