NEW ORCRITICAL SPECIES OF ACER. 15 
M. CASTANEA. M. Bigelovii, Greene, Man. 222, not of Gray. 
Usually a foot high, not rarely ever taller, the deeply simply 
and regularly pinnatifid or pinnatisect foliage nearly half as 
long : involucres hemispherical, more than 4 inch broad: achenes 
barely 2 lines long, short-columnar, or the yellowish-villous outer 
ones inclining to turbinate, the others chestnut-color, very 
smooth to the unaided eye, but the thick ribs under a strong 
lens obscurely and minutely scabrous; pappus fully 5 lines 
long, consisting of a lanceolate palea of 1 to 14 lines long, usu- 
ally whitish or pale, and a long slender barbellulate chestnut- 
brown awn. 
Confined to sandy elevations among the low salt-marshes of 
the shores of San Francisco Bay; the type specimens now in 
the California Academy collected by myself at West Oakland, 
10 May, 1883, and near Belmont, San Mateo Co.. 10 May, 1886. 
The longer and almost columnar achenes, and the long whitish 
pappus-pales, together with the great size of the plant, upright 
growth, and peculiarly maritime habitat impel the recognition 
of the species as distinct from its much more variable and diffi- 
cult ally, M. Bigelovit. 
M. tnstents. As tall as M. castanea, like it in habit, but 
leaves (in the only known specimens) narrowly oblanceolate 
and merely short-toothed; the tall scapes only 1 or 2, the 
heads round-ovate: achenes of outer series and of disk all alike, 
and all densely villous in lines (between the ribs), the ribs 
faintly scaberulous; palex of the pappus dark-colored, subulate, 
scaberulous and often more or less appressed-pubescent, scarcely 
a line long, entire, tapering to a stout subplumose awn of about 
3 lines. 
_ Known only in a single sheet of few specimens preserved in 
the California Academy, and labelled, in the handwriting of 
Mrs. Curran, as having been collected by myself in 1886. But 
this must have been, I think, a mere guess, and a wrong one. 
I could not have overlooked, in 1886, such pronounced specific 
characters as are here evident. 
