1. R. F. Averkina, Byull. Éksptl. Biol. i Med. 41, 2, 70–73 (1956). Original Russian pagination. See C. B. Translation.
2. A. Boyden and G. K. Noble, Am. Museum Novitates. 606, 1 (1933).
3. H. Braus, Arch. Entwickl. Mech. Org. 22, 564 (1906).
4. R. M. Clayton, Nature, 168, 120 (1951).
5. R. M. Clayton, Embryol. a. Exper. Morph. 1, 25 (1953).