168 ERYTHEA. 
Phacelia : circinatiformis, which was known only from 
Douglas’ collection. Where he obtained it seems doubtful; 
but it may yet, perchance, be found in Monterey Co., for the 
trend of rare plants, all through middle California, is north 
and south, and that in defiance of the fact that mountain 
ranges are crossed in keeping this line of distribution. This 
rule, hints of which began to be noted by me ten years ago, 
was strengthened by the study of the Mt. Hamilton Flora, 
and is further confirmed by what was seen on Mt. Diablo. 
Capnorchis chrysantha, Monolopia gracilens, Calochortus 
splendens, and some others, are in the Coast Range south- 
ward, but at or near Santa Cruz they abandon the seaboard 
hills, taking a northward line and reappearing on these 
mountains of the interior. Psoralea Californica and Eschs- 
cholizia ambigua ave local plants as far as known, whose 
other stations, seemingly much isolated, are away to the 
southward of Mt. Diablo. But a peculiar leap to the east- 
ward is made by an otherwise quite local plant; for Silene 
verecunda, of the peninsular sandy hills about San Francisco 
seems to have planted itself on the topmost peak of Mt. 
Diablo. However, plants growing from seed of the 
Diablo specimen have a behaviour of their own, and if 
brought into flower alongside the type of the species, may 
possibly overthrow my present view that they are specifically 
identical. 
At present only three of the Mt. Diablo plants may be 
claimed as endemic on this summit. They are Streptanthus 
hispidus, Sanicula saxatilis, and Helianthella castanea. 
Campanula exigua, discovered on Diablo in the summer of 
1836 by Mr. Rattan,—who, by the way, was the first botanist 
to explore this summit after the times of Brewer and Bolander 
—has since been found on Tamalpais and Hamilton, but is 
certainly a mountaineer, and not likely to be found on sum- 
mits much less elevated than these. 
The appended list of 156 species will be seen to fall far 
short, numerically, of the Mt. Hamilton list; and this notwith- 
standing that we attribute to Diablo a moister climate and 4 
