1. Fulton, T. W., Twenty-sixth Ann. Rep. Fish. Board Scotl. (1909).
2. Garstang, W., Mar. Biol. Ass. Internat. Rept. I [Cd. 2670] (1905).
3. Borley, J. O., ibid., Rept. IV [Cd. 6125] (1912).
4. Blegvad, H., J. du Conseil, 8, 161 (1933).
5. Allen, E. J., J. Mar. Biol. Ass., 11, 380 (1917).