the presence of this notch causes the marginal area of the 
petal to be somewhat ruffled or crumpled. I have very 
rarely observed anything similar to this condition in 
Caularthron bilamellatum. 
In the general shape of the hollow processes or ‘‘horn- 
like calluses*’ which arise from the disk of the lip and 
which have been used as the outstanding generic charac- 
ter, there is evident little variability from specimen to 
specimen, albeit some variation in relative size may be 
seen. Similarly, there is no significant morphological 
difference between these processes in Caularthron bicor- 
nutum and C. bilamellatum. 
Unlike the concept Caularthron bilamellatum, C. bicor- 
nutum does not have a large synonymy. This is due 
partly, perhaps, to the greater variability in the former 
than in the latter species. 
In 1925, Schlechter described Diacrium amazonicum 
from material collected in Brazil. The type material of 
Diacrium amazonicum is no longer extant, but a study 
of the type description convinces me that Schlechter 
specified no differences which, with the material at hand 
today, we could not easily accommodate in Caularthron 
bicornutum. Pabst (loc. cit.) determined a specimen 
(Froes 21541) from the Rio Negro in Amazonian Brazil 
as representing Diacrium amazonicum and published a 
diagnostic drawing of the floral parts. This drawing like- 
wise shows no character which could serve to distinguish 
the plant from Caularthron bicornutum. 
Type cottection: Cult. Hort. Wentwlorth], from Trinidad (Herb. 
Kew). 
Curtivarep: (Herb. Rehb. 898); Hort. Rucker, May 27, 1840 
(Herb. Rehb. 899; Herb. Ames 69096a); ‘“‘from the type plant of 
Gard. Chron. 1887, pt. 2, p. 45, fig. 11,’ Hort. Kew, May 1887, 
R.A. Rolfe s.n. (Herb. Kew); Botanic Station, Grenada, W.I. ‘‘Orig- 
inally from Trinidad,’’ April 14, 1906, W. EH. Broadway s.n. (Herb. 
Ames 7906, 7907). 
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