guide-line for generic delimitation is to be found in the 
inner structure of the lip. 
Every systematic study yields surprising information. 
Old generic names long in synonymy have to be resur- 
rected, for some wrongly placed species new genera have 
to be established, while the fate of those ‘‘aberrant ty pes”’ 
is postponed until the last paragraph has been written on 
the subject. The generic names Sarcanthus and Camaro- 
tis have to give room to Cleisostoma and Micropera be- 
cause of illegitimacy and priority respectively. 4 scochilus, 
Grosourdya and Cleisomeria after typification can again 
stand among recognized genera, while Cryptopylos, Por- 
rorhachis and Sarcophyton together with a few others 
are proposed for the first time to accommodate species 
in genera with characters of their own. 
In the following commentaries the genera are arranged 
alphabetically for an easy reference. A systematic ar- 
rangement of all genera according to their probable phy- 
letic affinities together with a key to facilitate identifica- 
tion will comprise the final paper in this series. 
Acknowledgments 
The taxonomic conclusions and nomenclatorial de- 
cisions presented in this paper are made possible by the 
cooperation of many friends and colleagues. For the per- 
mission and privilege of studying the numerous indis- 
pensable type materials kept in their institutions, I am 
indebted to Dr. J.P.M. Brenan and Miss Jean Bowden, 
The Herbarium, Royal Botanic Gardens, Kew, to Pro- 
fessor Dr. C.G.G.J. van Steenis, Rijksherbarium, Lei- 
den, to Dr. R. Ross, British Museum of Natural His- 
tory, London, to Professor Dr. Karl Rechinger, Natural 
History Museum, Vienna, and to Dr. M. N. Halle, 
Museum National d’Histoire Naturelle, Paris. For his 
continuous advice, interest and support my heartfelt 
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