216 CALIFORNIA .ACADEMY OF SCIENCES [Proc. 4TH SER. 
tation. The forms of this species which occur in the dry region 
are usually rather low and covered with small leaves of a 
decidedly gray color, due to the heavy covering of trichomes. 
Those forms which occur higher up in the transition and 
moist region are larger, sometimes attaining the size of small 
trees. On these the leaves are larger and with a much lighter 
covering of plant hairs. Species of Euphorbia occur to some 
extent in all of the regions, but are most abundant in the dry 
and lower transition, the species which occur here being for 
the most part bushy in character with small and inconspicuous 
leaves. The species which occur above the transition region 
are mostly procumbent herbaceous forms. Of the remaining 
genera Acalypha and Hippomane are the most important. 
Acalypha is represented by fourteen species and varieties, all 
of which are endemic. They are found for the most part in 
the transition and moist regions. Hippomane Mancinella 
occurs in various habitats, halophytic, xerophytic, and meso- 
phytic, with apparently no decided change in form in any of 
them. 
The Celastraceae have but a single representative, Maytenus 
obovata, bushes of which form a very important element of the 
flora of the dry regions, especially in the neighborhood of the 
coast. It occurs more or less abundantly throughout the dry 
and transition regions, in the first of which it is about the only 
green bush of any size during a great part of the year. 
The Sapindaceae are one of the smaller families in number 
of species, but are important from the fact that Cardiospermum 
furnishes a rather important herbaceous liane and Sapindus 
Saponari the largest forest tree found on the islands. The 
Rhamnaceae are represented by Discaria pauciflora, bushes of 
which occur abundantly in the lower parts of the dry regions. 
Outside of a few herbaceous forms, Gossypium barbadense ts 
the most important member of the Malvaceae. Bushes of this 
species occur in greater or less abundance in the dry and transi- 
tion regions. 
The Cactaceae are represented by several species of Cereus 
and Opuntia, most of which form rather striking elements of 
the flora. Both genera have both bushy and arborescent 
species, and are found for the most part in the dry and transi- 
tion regions. 
