270 f PITTONIA. 
Guajuco, Nuevo Leon, Mexico, 1880, Edw. Palmer (n. 677), 
distributed as Actinella linearifolia, from which its green (not 
silvery-canescent) herbage, and broader obtuse leaves, as 
well as its mode of branching. thoroughly distinguish it. 
RYDBERGIA. 
Stout but low upright sparingly branched alpine woolly 
perennials, with very large heads with long and narrow 
spreading yellow rays. Bracts of the low-hemispherical in- 
voluere all alike, distinct, herbaceous, in several series, loose, 
woolly. Receptacle broad and hemispherical. Rays 15 to 
30, an inch long or somewhat less, linear-cuneiform, broadest 
and deeply 3-toothed at apex. Pales of the pappus white 
(not transparent as in Tetraneuris), elongated-lanceolate and 
sleuderly acuminate. 
Dedicated to Mr. Per Axel Rydberg. 
1. R. GRANDIFLORA. Actinella grandiflora, Torr. & Gray, 
Journ. Bost. Nat. Hist. Soc. v. 110 (1847). Alpine summits 
of the Rocky Mountains from Colorado to Montana. 
2. R. GLABRATA.  Aclinella grandiflora; var. glabrata, 
Porter & Coulter, Fl. Colo. 76 (1874). Actinella Brandegev 
Porter in Gray, Proc. Am. Acad. xiii. 373 (1878). High 
peaks cf southern Colorado to southern New Mexico. 
That Sir William Hooker's PrcmApENI1A is alien to both 
the foregoing is doubly attested by its peculiar habit, and 
the extremely different involucre. This organ is distinetly 
double, being made up of an outer series of narrow and 
rigid bracts which unite at base and form a sort of cup en- 
closing an inner series of separate broader ones. Their rays 
are few, short, cuneiform and with a less simple nervation 
than those of Tetraneuris. As in that genus the northern : 
and typical species are perennial, while several of the more — 
southerly ones are annual. e 
