Coast Islands of California. 277 
tago hirtella and Scirpus riparius are plants of the northern coasts mainly 
and their rareness on San Miguel indicates that they formed no part of the 
old flora of the island, but have appeared there in recent times, owing to the 
course of winds and currents. In the subjoined list‘) species endemic to Santa 
Catalina, San Clemente are in italics; species closely connected with continental 
ones, perhaps mere varieties of them, are designated by an asterisk. 
Astragalus Nevinii A. Gray. Hemizonia Clementina T.S.Brandegee. 
*Ceanothus arboreus Greene. Lavatera assurgentifiora Kell. 
*Cercocarpus Traskae East. Phacelia Lyoni A. Gray. 
*Crossosoma californica Nutt. Lyonothamnus floribundus A, Gray. 
*Eriogonum giganteum Wats. Malacothrix foliosa A. Gray. 
Eriophyllum Nevinii A. Gray. » insularis Greene. 
Galium catalinense A. Gray. Plantago dura Morris. 
Gilia Nevinii A. Gray. Quercus tomentella Engelm. 
The fact that the majority of insular species are identic with those of the 
mainland and that only a few genera and species are endemic to the islands 
argues for a former land connection. The flora of the islands may be looked 
upon as the survivors of a coast flora, which was widely distributed along the 
shores of California before the period of subsidence, when these islands, which 
are approximately parallel with the present coast line, were isolated by the 
general subsidence of land beneath the sea. When the subsidence occurred, 
the old California coast flora was preserved almost unchanged on the islands 
and, therefore, enables us to determine the character of the original endemic 
coast flora, while on the mainland after the separation of the islands the species 
were subjected to the influence of new elements which migrated into the 
Californian area from the north, south and east after the close of the glacial 
Period, Excluding weeds and other species of wide distribution, we have in 
the above list an enumeration of species which represent collectively the 
ancient coastwise flora of California. According to this view all species 
Of the islands did once inhabit the mainland, but the existing differences are 
due to the destruction of species, or their transformation in their struggles 
with invaders. There are quite a number of rare and peculiar forms such as 
Pinus Torreyana found struggling for existence on the mainland. These = 
probably remnants of Pliocene indigenes still undestroyed, but ready to perish. 
The distribution of the genus Lavatera also is explained by reference to > 
Conditions. Several species of Zavatera perhaps existed all over yy ne 
WON of California which ..is represented by the present chain © ie = 
They have all been destroyed by change of environment except those A 
®R the islands and thus saved from the effects of invasion and aridity *). 
en ; , te XXXVI: 
) Bmen, S.B.: A Sketch of the Flora of southern Be nn Gazette 
ri ibli ; joras is . 
a Eee hast Tlnda, af Calornin in Rein. to ren 
Changes of physical Geography. American Geologist I: 76—81. 
264, 
1888. 
