18. Stebbins, G. L. Jr. 1950. Variation and Evolution in Plants. 
New York, Columbia University Press, 
19. Swamy, B. G. L. 1948. Vascular Anatomy of Orchid Flowers. 
Bot. Mus. Leafl. Harvard Univ. 13: 61-95. 
20, Swamy, B. G. L. 1949. Embryological Studies in the Orchid- 
aceae II. Embryogeny. Amer. Midland Nat. 41: 202-282, 
21. Takhtajan, A. L. 1954. Origins of Angiospermous Plants. Soviet 
Sciences Press. (Translation) 
29, Vermeulen, P. 1955. The rostellum of the Ophrydeae. Amer. 
Orchid Soc. Bull. 24: 239-245. 
28. Vermeulen, P. 1959. The Different Structure of the Rostellum 
in Ophrydeae and Neottieae. Acta Bot. Neerl. 8: 338-355. 
24, Vogel, S. 1959. Organographie der Bliten Kaplindischer Ophry- 
deen. Akad. Wissensch. u. Lit., Mainz; Abhandl. Mat. -Nat. 
Klasse; Nos. 6 u. 7. 
ILLUSTRATION CREDITS 
All plates and figures were drawn by Mr. Elmer W. Smith. 
Plates VIII, XI, XIII, XIV, originals. 
Plate IX, fig. 1, fig. 6,after Bauer & Lindley, Illustrations of Orchid- 
aceous Plants. 
fig. 2, fig. 3, after Pfitzer, Orchidaceae-Pleonandrae. 
fig. 4, original. 
fig. 5, after Miller and Krinzlin, Abbildungen der in Deutsch- 
land und den angrenzenden Gebieten vorkommenden Grund formen 
der Orchideen. 
Plate X after Swamy, Embryological Studies in the Orchidaceae II. 
Plate XII: Apostasia papuana after Smith, Nova Guinea XII, 
Orchidaceae. 
Cranichis crumenifera and Vanilla anomala, originals. 
Cephalanthera alba after Bauer and Lindley l.c. 
Corycium crispum and Satyrium saxicolum after Vogel, 
Organographie d. Bliten Kaplindischer Ophrydeen. 
Vanilla Griffithii var. formosana after Ito, Icon. Jap. 1: 
t. 1, 1911. 
Cypripedium Calceolus after Hegi, Il. Fl. Mitteleuropas. 
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