1. ASHTON, N. (1952). Brit. J. Ophthal., 36, 465.
2. BEAuvIEUX, J., and RISTITCH, K. (1924). Arch. Ophtal., 41, 352.
3. Text-book of Ophthalmology;DEYL, J.;Anat. Anz,1896
4. DEYL, J. (1956). Ibid., 40, 45.
5. , and COLLETrE, J. M. (1955). Ibid., 39, 220.