oe 
APOSTASIACEX OF THE MALAY PENINSULA. 365 
many other groups. The bifid lamella of the back of the spur 
in Cleisostoma seems to correspond to the hypochilary callus of 
many orchids. From its being often glandular pubescent on 
the lower face I imagine that its function is to secrete nectar. 
Both of these organs differ considerably in size, extent of 
development, and form, so that it is difficult to use them as 
means of separation of the genera. But there is another 
distinguishing mark which is much easier to utilize. In 
Sarcanthus the lateral lobes of the lip are usually short, and do 
not meet in the middle line; the terminal lobe is often small, 
and it is generally more or less channelled; so that a depression 
leads from it into the horizontal spur. In Clezsostoma we have 
the short wall like lateral lobes meeting or nearly meeting in 
the middle lobe; while the mid-lobe is oval or reniform, and 
barred off from the pendent spur by the lateral lobes. The 
structure of the Cleisostoma lip is that of the Calceolaria section 
of Saccolabium, except that the spur is usually longer and 
contains the lamellary callus. With these characters there is also 
a difference in colouring, which though not of any great generic 
importance, yet is worth noting. In Sarcanthus the prevailing 
colouring is sepals and petals green with a more or less distinct 
longitudinal central red bar, and lip violet or pale rose; 
whereas in Cleisostoma the ground colour of the whole flower is 
yellow, and it is irregularly marked with dark red spots. 
Of the Indian Cleisostomas, Cleisostoma andamanicum, Hook. 
f., C. Mannii, Reichb. f., C. bicuspidatum, Hook. f., C. spicatum, 
Lindl, ©. latifolium, Lindl. C. parvum, Ridl., C. maculosum, 
Lindl., OC. crassum, Ridl., C. uteriferum, Hook. f., and probably 
most of the others in the ‘ Flora of British India,’ possess nearly 
all these characters, and form a group which can be easily 
distinguished from Sarcanthus and Saccolabium. I imagine 
Saccolabium Helferi, Hook. f., Ic. Pl., t. 2130, will prove to be a 
Cleisostoma; it has the form and habit as well as the shape of 
the lip of Cleisostoma, though the callus appears to be sometimes 
wanting. 
Crersostoma LatirotruM, Lindl., Bot. Reg. (1840) Misc., p. 60. 
Hab. Singapore: (fide Lindley, l.c.). 
Malacca: Griffith. 
Perak: Wray. 
Pahang: Temerloh ! 
Also Sumatra, at Djambi! 
