THE WORKS OF FRANCIS MAITLAND BALFOUR. VOL. IV. Memorial Edition. Cambridge: PRINTED BY C. J. CLAY, M.A. AND SON, AT THE UNIVERSITY PRESS. Memorial Edition. THE WORKS OF FRANCIS MAITLAND BALFOUR, M.A., LL.D., F.R.S., FELLOW OF TRINITY COLLEGE, AND PROFESSOR OF ANIMAL MORPHOLOGY IN THE UNIVERSITY OF CAMBRIDGE. EDITED BY M. FOSTER, F.R.S., PROFESSOR OF PHYSIOLOGY IN THE UNIVERSITY OF CAMBRIDGE; AND ADAM SEDGWICK, M.A., FELLOW AND LECTURER OF TRINITY COLLEGE, CAMBRIDGE. VOL. IV. PLATES. London: MACMILLAN AND CO. 1885 [_The Right of Translation is reserved._] LIST OF PLATES, ILLUSTRATING THE ORIGINAL MEMOIRS IN VOL. I. PAGE Plate 1. Development of the layers of the blastoderm 29 " Disappearance of primitive groove 41 " 2. Development of blood-vessels 47 " 3.} Preliminary account of development of Elasmobranch " 4.} Fishes 60 " 5. Comparison of early stages of Vertebrates 112 " 6. Development of Elasmobranch Fishes. ch. II. 222 " 7. " " " " III. 246 " 8.} " 9.} " " " " IV. 286 " 10. " " " " V. 298 " 11.} " 12.} " " " " VI. 315 " 13. " " " " VII. 361 " 14. " " " " VIII. 378 " 15.} " 16.} " " " " IX. 397 " 17.} " 18. " " " " X. 446 " 19. " " " " XI. 460 " 20.} " 21.} " " " " XII. 479 " 22.} " 23.} Development of spinal nerves in Elasmobranchs 168 " 24.} " 25.} Structure and development of Vertebrate ovary 549 " 26.} " 27.} " 28.} Head-kidney in embryo Chick 618 " 29. Early development of Lacertilia 644 " 30.} " 31.} Development of Araneina 668 " 32.}