336 Willis. — Further Evidence for Age and Area; 
I. The Orchids of Jamaica. 
In order to bring in a country as far removed from Ceylon and New 
Zealand as possible, I have taken Jamaica, of which a detailed flora is in 
course of publication by Messrs. Fawcett and Rendle ( 4 ), and have used the 
first volume, which contains the Orchids, a family exceptionally well known 
in the country. 
To go into great detail is unnecessary, and I shall simply describe the 
method used and the results obtained. Taking a sheet of squared tracing- 
paper, I placed it over a large map of the island, and with the aid of the 
large official map identified and marked the localities given, 162 (different) 
in all. A few of these I was not able to identify, especially such as Ramble, 
Retreat, and Belvidere, which appear upon the map in dozens of places. 
I thus noted for each species the squares in which it occurred, and for the 
unidentified localities I have simply allowed another square. This in actual 
fact adds almost exactly a square for every other species, but acts equally 
on all alike. Each of the larger squares of the tracing-paper covered an 
area approximately 6f miles square. 
To make a fair test of my hypothesis, and to enable comparison with 
Ceylon and New Zealand, I have divided the Orchids (194 in all) into three 
groups — those endemic to Jamaica, those found in Jamaica and Cuba only, 
and those with wider distribution than this (wides). Adding up for every 
species the number of squares for which it is recorded, we get : 
Table I. 
No. of squares. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
Total 
Average No. of squares occupied 
Wides. 
7 
1 1 
13 
15 
12 
10 . 
5 
5 
7 
1 
104 
5‘7 
Jamaica - Cuba . 
1 
2 
2 
2 
3 
4 
15 
4-5 
Endemic. 
30 
12 
10 
4 
7 
5 
3 
1 
1 
75 
3*o 
This result, it will be at once seen, is exactly parallel to that obtained 
for Ceylon and New Zealand. The wides occupy the largest area, the 
