668 The American Naturalist. [August, 
The harmonic relation of the floras of the different islands, 
which, as we have seen, appears to have such an interesting 
bearing upon the former possible connection of the islands 
with each other, is shown not only by Euphorbia viminea, but 
by various other endemic species and groups of species of the 
same and other genera and orders. 
All the Galapageian species of Euphorbia for instance, with 
the exception of E. amplesicaulis Hook. fil., form a closely re- 
lated group, doubtless having a comparatively recent common 
ancestry ; but most of these forms are characteristic of particu- 
lar islands. The same is eminently true of the different species 
of Acalypha. The Borreriz of the Galápagos Islands also form, 
for the most part, a close group of very nearly related species, 
or, perhaps, better varieties of one polymorphous species, all 
of which have probably diverged from a uniform parent stock 
after the separation of the insular floras from that of the main- 
land and from each other. Here, however, we find in some 
instances the same form upon two or more of the islands, as 
though transportation of the seed had offered somewhat less 
difficulties than in the case of Euphorbia viminea.” The forms 
of Euphorbia viminea Hook. fil. are as follows: 
Forma Albemarlensis (typica).-—Albemarle Island ; collected 
first by Macrae, and again by Dr. Baur, on the southern end of 
the island in July, and on the eastern side in August, 1891. 
Forma Jacobensis.—Collected by Dr. Baur near Orchilla Bay, 
Northern James Island, August, 1891. 
Forma Castellana.—Collected on Tower Island, by Dr. Baur, 
September 1891. 
Forma Chathamensis—Collected on Chatham Island, lower 
region, southwest end, by Dr. Baur, June, 1891. 
Forma Carolensis—Collected on Charles Island, by Ander- 
son, 1852. 
Forma Barringtonensis.—Collected on Barrington Island, by 
Dr. Baur, July, 1891. 
Forma Jervensis—Collected on Jervis Island, by Dr. Baur, 
August, 1891. 
TI do not give here the description of these varieties, which may be looked up 
in the original paper. 
