University Press for a diagram (fig. 28) from Mr J. W. Jenkinsonãs Experimental Embryology ; and to the Cambridge University Press for a number of figures from Professor Henry Woodsãs Invertebrate Palaeontology , for one (fig. 210) from Dr Willeyãs Zoological Results , and for another (fig. 321) from ãThomson and Tait.ã
Many more, and by much the greater part of my diagrams, I owe to the untiring help of Dr Doris L. Mackinnon, D.Sc., and of Miss Helen Ogilvie, M.A., B.Sc., of this College.
DãARCY WENTWORTH THOMPSON.
UNIVERSITY COLLEGE, DUNDEE.
December, 1916.