138 Robinson and Greenman—Galapagos F lora. 
with each other, is shown not only by Auphorbia viminea, 
but by various other endemic species and groups of species of 
the same and other genera and orders. 
All the Galapageian species of Huphorbia for instance, with 
the exception of £. amplexicaulis Hook. fil., form.a closely 
related group, doubtless having a comparatively recent com- 
mon ancestry; but most of these forms are characteristic of 
particular islands. The same is eminently true of the differ- 
ent species of Acalypha. The Borrerte of the Galapagos 
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 mainland and from each 
other. Here, however, we find in some instances the same 
form upon two or more of the islands, as though transpor- 
tation of the seed had offered somewhat less difficulties 
than in the case of Huphorbia viminea. 'The peculiar interest 
which attaches to the individual occurrence of these nearly 
related forms of various groups upon the different islands, 
certainly warrants the publication of the following more 
detailed descriptions and complete list of Dr. Baur’s plants. 
The forms of Huphorbia viminea Hook. fil. are as follows: 
Forma ALBEMARLENSIS (typica). Internodes 4 to 54 lines long: 
. leaves of the stem and of the slender elongated branches 2 to 54 
lines long, half line broad, reddish in the dried state and usually 
paler beneath, linear with dilated rounded rarely retuse tip ; 
margins except near the apex strongly revolute; leaves of the 
fascicles and scarcely developed branchlets similar but only 1 to 2 
lines long and more distinctly retuse at the apex.—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 Jacopensis. Internodes 3 to nearly 6 lines long: leaves 
of the stems and branches 3 to 6 lines long, half a line broad, 
scarcely dilated at the apex ; fascicled leaves as in the preceding. 
—Collected by Dr. Baur near Orchilla Bay, James Island, 1891. 
peewee from the last by its slightly longer and less dilated 
eaves. 
Forma CasTELLANA. Internodes 24 to 4 lines long: leaves of 
stem and branches 3 to 4 lines long, three-fourths lines broad ; 
a line in width at the dilated apex, truncate and retuse, much 
firmer and thicker than in any of the other forms, very pale above, 
whitened beneath; fascicled leaves very short, 1 to 14 lines long. 
—-Collected on Tower Island, by Dr. Baur, September, 1891. 
Forma CuarHaMeEnsis. Internodes from 3 to 54 lines long: 
leaves of the stem and branches 44 to 7 lines long, half line broad, 
slightly dilated at the truncate or often retuse tip, pale in the 
