316 TlMEHRI. 
hard and brittle, deeply channeled. Texture rigid, coriaceous. Colour 
pale, pellucid, green. Venation fine, the areolae oblong and directed to 
the margin at an angle of 450., translucent. The terminal and 4-6-7 or 
8 pair of the upper lateral pinnae fertile. Corpuscular covering of 
the sporangia coffee coloured, the segregates obtusely angular, star- 
shaped or irregularly spurred. 
Communal, covering extensive areas of the marshy 
coast region, and banks of the mouths of the rivers. 
Though also large, a smaller and more slender but 
more rigid plant in all its parts than the preceding, with 
few distant pinnae, only the upper ones of which are 
ever fertile, and with very different shaped and coloured 
corpuscles. 
The Genus Thurnia. — This genus, founded by Sir 
JOSEPH HOOKER on two species collected by Mr. 
JENMAN and Mr. IM THURN in the neighbourhood of 
the Kaieteur Fall, has already been described in 
Timehri (Vol. 1, p. 249 and 309.) The illustrations 
which should have been published at the same 
time were unfortunately delayed and omitted. They 
are now however given. The opportunity may be taken 
to add, as to the history of one of these species, 
T. Jenmani, that during a recent visit to the Kaieteur, 
in extremely dry weather, it was found that the 
plant, usually so abundant in the bed of the Potaro, had 
then almost disappeared, temporarily, under the influence 
of the drought. 
Balata, — The following extract from a letter by Mr. 
H. H. SMYTHE, of New York, bears on a subject of 
considerable interest in this colony. 
" For years I have tried in vain to learn how Balata is coagulated, et 
