XX CONTENTS. 



PAfiK 



X. On the Existence of Acari between the Laminw uf Mica in Optical 

 Contact. By Sir David Brewster, K.H., D.C.L., F.R.S. 

 (With a Plate, VI.), ...... 95 



XI. On Certain Vegetable and Mineral Formations in Calcareous Spar. 

 By Sir David Brewster, K.H., D.C.L., F.R.S. (With a Plate, 

 VIL), . ' ^97 



XII. Memoir of the Life and Writings of Robert Whytt^ M.D.y Professor 

 of Medicine in the University of Edinburgh from 1747 to 17G6. 

 By WiLLmi Seller, M.D., F.R.S.E., Fellow of the Royal 

 College of Physicians of Edinburgh, . . .09 



XIII. Exjjerimental Inquiry into the Laios of the Conduction of Heat in 



Bars., and into the Conducting Poioer of Wrought Iron. By 

 James D. Forbes, LL.D., D.C.L,, F.R.S., V.P.R.S. Ed., Corre- 

 sponding Member of the Institute of France, Principal of the 

 United College of St Salvator and St Leonard, St Andrews, . 133 



XIV. On the Density of Steam. By Professor W. J. Macquorn Ran- 



KiNE, C.E., LL.D., F.R.SS. Lond. and Ed., &c., . 147 



XV. On the Secidar Cooling of the Earth. By Professor William Thom- 

 son, LL.D., F.R.S., F.R.S.E. (With a Plate, VIII.) . 157 



PART II. (1862-63.) 



XVI. On the Representative Relationships of the Fixed and Free Tunicata, 

 regarded as two Sub-Classes of equivalent value; with some 

 General RemarJcs on their Morphology. By John Denis Mac- 

 donald, R.N., F.R.S., Surgeon of H.M.S. " Icarus." Com- 

 municated by Professor Maclagan. (With a Plate, IX.), . 171 



XVII. On the Zoological Characters of the Living Clio caudata, as compared 

 with those of Clio borealis given in Systematic Works. By John 

 Denis Macdonald, R.N., F.R.S., Surgeon of H.M.S. " Icarus." 

 Communicated by Professor Maclagan. (With a Plate, IX. 

 fig. 3), 185 



