[32] O. Hertwig, Arch. mikr. Anat. xi. (1874).
[33] R. H. Traquair, Trans. Roy. Soc. Edin. xxxix. (1899).
[34] Cf. E. S. Goodrich, Quart. Journ. Micr. Sci. xlvii. (1904), 465.
[35] R. H. Traquair, Journ. Anat. Phys. v. (1871) 166; J. S. Budgett, Trans. Zool. Soc. Lond. xvi. 315.
[36] T. W. Bridge, Trans. Zool. Soc. Lond. xiv. (1898) 350; W. E. Agar, op. cit.
[37] J. V. Boas, Morphol. Jahrb. vi. (1880).
[38] Cf. F. Hochstetter in O. Hertwig Handbuch der Entwickelungslehre.
[39] C. v. Kupffer, Studien z. vergl. Enlwickelungsgeschichte der Cranioten.
[40] Cf. F. K. Studnička’s excellent account of the parietal organs in A. Oppel’s Lehrbuch vergl, mikr. Anatomie, T. v. (1905).
[41] 2. F. K. Studnička, S.B. böhm. Gesell. (1901); J. Graham Kerr, Quart. Journ. Micr. Sci. vol. xlvi., and The Budgett Memorial Volume.