Itt} SHREVE—JAMAICAN HYMENOPHYLLACEAE 187 
are confined to spots where the conditions are made favorable 
by very local topographic or related causes; on rocks near to 
waterfalls, about the bases of trees in deep shade, and on the lower 
sides of moss-covered logs the conditions of humidity and water- 
supply resemble locally the climatic conditions of the mountain 
forests. The Hymenophyllaceae which occur at low altitudes are 
chiefly small species of Trichomanes which have a creeping rhizome 
and simple or pinnatifid leaves not exceeding 3 cm. in length. The 
forms which do not range above 914 m. are all of the description: 
Trichomanes punctatum Poir. Trichomanes Krausii Hook. & Grev. 
Trichomanes sphenoides Kze. Trichomanes membranaceum L. 
Trichomanes polypodioides L. 
CLIMATIC CONDITIONS IN THE RAIN FOREST.—Some notion of 
the climatic conditions in the zone of maximum occurrence of the 
Hymenophyllaceae may be had from the series of records kept at 
Cinchona since 1871. The position of Cinchona on the leeward 
slope of the main ridge of the Blue Mountains, together with the 
exposure of the instruments in an open lawn, keeps this record from 
giving a full indication of the moistness of the rain forest itself. 
The writer judges from personal experience that the rainfall is 
between 20 and 30 per cent greater and the number of rainy days 
between ro and 1 5 per cent greater in the forests than is indicated 
in the following figures for Cinchona: 
Sep.| Oct. | Nov. | Dec. | Year 
Jan. | Feb. | Mar.) Apr.| May | Jun.’| Jul. | Aug. 
erence Ce 
Rainfall .. 7.26|4.09|5. 32/6. 36/11. 10|8.00|3. 89/8. 29|9. 22|18. 57/12. 32/11. 11/104.77 
Ry. MAYS ../14.1/12 5|12.8/12 918.1 |13.5|10 Birr. 2!16.1/21.4 18.3 16.2 |179.4 
Humid. . . . 84.1/83.1/83.9|83 4\85.2 |84.8|79.6)/80 4/84 488.9 |86.0 86.3 | 84.1 
In the course of some general work on the Blue Mountain region 
hot yet published, the writer had occasion to expose a combined 
thermograph and hygrograph in a number of localities, and the 
record sheets figured herewith give a graphic conception of the 
daily march of temperature and humidity under natural forest 
Conditions. The instrument was supported on an open framework 
one meter above the ground and sheltered by a canvas cover spread 
Widely above it so as to keep off rain but permit a good circulation 
