PN LEEN LEN APERAR Ter Fey CET ee ES E E Ea | PEN, 
SLOE eee eT 
FENSTER 
o i ia a a a E y ne 
. A atest ate ENT? 
1878. | Walks Round San Francisco, 787 
on the hill-side, and the little song-sparrows flit before us from 
stone to stone as we advance upwards. 
While standing on a spur near the summit, gazing on the 
panorama of the city and its surroundings, my son, who is bent 
on exploring, suddenly shouts from behind a large rock, “ Papa, 
here’s a fern!” And sure enough, in that dried out spot, in the 
crevices of a rock five hundred feet above the sea, far from all 
moisture, grow numerous examples of a thick-leaved simply pin- 
nate fern. We secure some of the plants, and on enquiring from 
our botanical friends, find that the curious fern is known as 
Polypodium scouleri. 
It is a rough descent over the sun-baked soil and slippery bents 
of grass from Sweeney’s Peak to the Laguna, which nestles in 
the deep valley between it and the opposite peak. 
Castilleta parviflora and Convolvulus occidentalis are almost the 
only flowers we find on our way down, and as the water in the 
lake is too low and too free from vegetation to give us a chance 
to collect Ancylus, we direct our course along the flume to the 
lower lake, passing through a dense thicket of Siyum marianum, 
or blessed thistle, a plant which, since its probable introduction 
by the Spaniards, has increased to the dimensions of a nuisance. 
At last, on the stems of Szum latifolium we find a few Ancyli, 
tiny little vesicles of shelis, which would certainly be overlooked 
by any one not specially searching for them, since they are only 
about a third of an inch long, almost colorless, applied to the 
stem by the whole of their under surface, and very much flatter 
above than their namesakes of the ocean beach. These “ fresh- 
water limpets,” it may be as well to remark, are but distant rela- 
tives of the real limpets, they are “ Pulmonata, "or air breathers, 
like the fresh-water snails and the land snails, while the limpets 
are provided with gills like other univalves of the ocean. This 
is one of those cases, so many of which occur in the animal 
kingdom, where considerable outward resemblance masks radical 
structural differences. 
As this is a rambling paper, and the last that we shall piece 
together from our rambles on this wind-stricken peninsula, we 
will lengthen out our walk northwards until we reach the Seal 
Rock road, along or near which we will trudge till we descend 
to the ocean beach close to the extensively-advertised Seal Rock. 
Seal Rock is one of the greatest lions of San Francisco, or 
VOL, X11.—no, XI. 53 
