CONTENTS. 
PART II. 
VII. On the Structure and Development of Lepiclosteus. By F. M. Balfour, LL.D., 
F.R.S ., Fellow of Trinity College , Cambridge, and W. N. Parker, Assistant 
in the Biological Laboratory of the Normal School of Science, South 
Kensington . page 359 
VIIT. On the Development of the Shull in Lepidosteus osseus. By W illiam Kitchen 
Parker, F.R.S. . .443 
IX. On the Vibrations of a Vortex Ring , and the Action upon each other of Two 
Vortices in a Perfect Fluid. By J. J. Thomson, B.A., Fellow of Trinity 
College, Cambridge. Communicated by Lord Bayleigh, F.R.S. . . . 493 
X. The Bakerian Lecture. — Chemical Theory of Gunpowder. By H. Debus, 
Ph.D., F.R.S. .523 
XI. On the Refraction of Plane Polarized Light at the Surface of a Uniaxal Crystal. 
By B. T. Glazebrook, M.A., Fellow and Assistant Lecturer of Trinity 
College, Demonstrator in the Cavendish Laboratory, Cambridge. Communi¬ 
cated by Lord Bayleigh, M.A., F.R.S. . 595 
XII. On the Results of Recent Explorations of Erect Trees containing Animal 
Remains in the Coal-formation of Nova Scotia. By J. W. Dawson, LL.D. 
F.R.S., C.M.G . 621 
XIII. Experiments to determine the Value of the British Association Unit of 
Resistance in Absolute Measure. By Lord Bayleigh, F.R.S., Professor 
of Experimental Physics in the University of Cambridge . 661 
XIV. On the Comparative Structure of the Brain in Rodents. By W. Bevan 
Lewis, L.R.C.P. (Bond.), Senior Assistant Medical Officer, West Riding 
Asylum, Wakefield. Communicated by Dr. Ferrier, F.R.S. . . . . 699 
Lndex to Part LI. 
747 
