126 THE THICK-LEAVED CLEISOSTOME. 
small, pear-shaped and distinct, at the end of a filiform caudicle attached to an oblong gland. In 
this respect the plant is at variance with other Cleisostomes, such species as we have examined having 
the pollen-masses in pairs, the lobes of which are unequal and plano-convex. 
We observe that the late Mr. Griffith enquires in his Notule (p. 358) why Cleisostoma is 
separated from Saccolabium and Sarcanthus. The differences among the three genera are these :— 
In Saccolabium the spur of the lip is one-celled, without any tooth at the foot of the column ; to 
Cleisostoma and Sarcanthus that peculiar process is essential. In Cleisostoma the spur is absolutely 
one-celled, while in Sarcanthus it is more or less completely two-celled. It is a question, no doubt, 
whether Blume’s genus Cleisostoma ought to be separated from Sarcanthus, but about the 
distinctness of Saccolabium we entertain no doubt. 
