subsequently by Burmann in 1759. A closer examination of 
Plumier’s drawing reveals at once that it is referable to the genus 
Pleurothallis R.Br. as it is understood today, and is conspecific 
with Pleurothallis floribunda (Lind1.)Lindl. Therefore, a retypi- 
fiction of Sve/is is necessary to prevent a mass transfer of some 
1,000 specific epithets from Pleurothallis which is inevitable if 
the old typification is maintained. 
In using this reasoning, Garay and Sweet in the Journal of the 
Arnold Arboretum 53: 528, 1972 have selected Humboldtia pur- 
purea Ruiz & Pavon as a new lectotype. 
ACKNOWLEDGMENTS 
My special thanks and appreciation are recorded here to the 
John Simon Guggenheim Memorial Foundation for their Ca- 
nadian Fellowship awarded to me in 1957 for the purpose of a 
monographic revision of the genus Sre/is. This same foundation 
has also provided extra financial help toward the preparation of 
the illustrations published for the first time in this paper. 
The financial help in the form of a grant from the American 
Orchid Society’s Fund for Education and Research and the con- 
tribution of Mr. Fritz Hamer of El Salvador, both of which 
helped to defray in part the publication costs of this paper, are 
here gratefully acknowledged. 
KEY TO THE GENERA OF THE SUBTRIBE 
PLEUROTHALLIDINAE 
bs) POUND 2) oe pet ce deve deus dee pear nena keees Z 
fa; Poninia A OF 6-09 S: s<scx gna veres oy kana d da ive mak 23 
2. Lip firmly adnate to column ................08. 3 
2a. Lip movably articulate with column ............. 5 
3. Flowers fleshy; lip adnate to base of column at a right 
BORG sec ade eee ne ee cea eee eeres Crocodeilanthe 
3a. Flowers membranaceous; lip parallel with column 4 
4. Column cylindric to clavate; stigma in front of column 
PAS. UG nee eee wads ee bee eae ed Lepanthes 
4a. Column trumpet-shaped; stigma terminal in center of 
obliquely truncate column ............... Salpistele 
5. Flowers not resupinate, i.e. lateral sepals and lip upper- 
TOS. yea ae eK a a ee be eee ae 6 
