CONTENTS. 
PART IT. 
X. On the Organization of the Fossil Plants of the Coal-Measures. — Part IX. By 
Professor W. C. Williamson, F.R.S page 319 
XI. New Determination of the Mechanical Equivalent of Heat. By James Prescott 
Joule, D.C.L. , LL.D., F.R.SS. L. and F., &c., President of the Literary and 
Philosophical Society of Manchester 365 
XII. On the Structure and Development of the Shull in the Common Snake (Tropido- 
notus natrix). By William Kitchen Parker, F.R.S. 385 
XIII. Addition to Memoir on the Transformation of Elliptic Functions. By A . Cayley 
Sadlerian Professor of Mathematics in the University of Cambridge . . 419 
XIV. The Croonian Lecture. — On the Structure of the Stylasteridce, a Family of 
the Hy droid Stony Corals. Bp H. N. Moseley, F.R.S., Fellow of Exeter 
College, Oxford, late Naturalist onboard H.M.S. ‘ Challenger’ . . . . 425 
XV. On the Development of the Parasitic Isopoda. By J. F. Bullar, B.A., Trin. 
Coll., Cambridge. Communicated by Dr. Michael Foster, F.R.S., Proelector 
of Physiology in Trinity College, Cambridge 505 
XVI. On the Placentation of the Apes, with a Comparison of the Structure of their 
Placenta with that of the Human Female. By Wm. Turner, M.B. (Fond.), 
F.R.SS. L. and E., Professor of Anatomy in the University of Edinburgh 523 
XVII. Observations on the Nervous System of Aurelia aurita. By Edward Albert 
Schafer, Assistant Professor of Physiology in University College, London. 
Communicated by W. Sharpey, M.D., LL.D., F.R.S. 563 
XVIII. On the Modifications of the Simple and Compound Eyes of Lnsects. By 
B. Thompson Lowne, F.R.C.S., Lecturer on Physiology at the Middlesex 
Hospital Medical School, Arris and Gale Lecturer on Anatomy and Physiology 
in the Royal College of Surgeons, &c. Communicated by Prof. W. H. Flower, 
F.R.S. 577 
XIX. A Tenth Memoir on Qualities. By A. Cayley, F.R.S., Sadlerian Professor 
of Pure Mathematics in the University of Cambridge 603 
