44 
J. C. ARTHUR 
It will be seen from this list that there is a remarkable coincidence 
in the distribution of the two forms. The range of the cedar-rust is 
nearly co-extensive with the range of the host, but the similar restric- 
tion of the Malaceous rust can not depend upon the aecial hosts, which 
are far more widely distributed. To make the geographic argument 
even more convincing it should be stated that no other unattached 
Gymnosporangial aecia or telia are known from the region in question. 
As the teliospores now found to be associated with the uredinia 
upon Chamaecyparis nootkatensis are of the general form and structure 
of certain other species of Gymnosporangium to be considered closely 
related, and as the structure and appearance of the uredinia conform 
to theoretical demands based upon analogy with the large group of 
rusts represented by Puccinia graminis, and furthermore as both 
structure and geographic distribution assure the probable association 
of Aecidium Sorhi as the alternate stage, it seems fitting to present 
the following synonymy and description of the species in its entirety. 
Gymnosporangium nootkatensis (Trelease) comb. nov. 
Uredo nootkatensis Trelease, Alaska Harr. Exped. 5: 36. 1904. 
Aecidium Sorhi Arthur, Bull. Torrey Club, 33; 521. 1906. 
Gymnosporangium Sorhi Kern, Bull. N. Y. Bot. Card. 7: 438, 191 1. 
Uredo Chamaecyparidis-nutkaensis Tubeuf, Nat. Zeits. Forst.-Landw. 2: 91. 1914. 
O and I. Described in N. Amer. Flora 7: 190-191. 1912. 
On Malaceae: 
Malus rivularis (Dougl.) Roem. Alaska, British Columbia. 
Sorbus occidentalis (S. Wats.) Greene, Washington; British Columbia. 
Sorhus scopulina Greene, Alaska. 
Sorhus sitchensis Roem. Alaska. 
II. Uredinia foliicolous, on yellow spots covering the whole leaf, subepidermal, 
round, 0.5 mm. across, bright orange fading to light yellow, prominently pulvinate, 
somewhat pulverulent, ruptured epidermis generally noticeable; urediniospores 
globose or obovate-globoid, 28-32 ix in diameter; wall pale yellow becoming colorless, 
moderately thick, 3-4 fx, finely and closely verrucose, appearing radiately striate, the 
pores 2, equatorial; pedicels colorless, somewhat persistent. 
III. Telia not seen; teliospores in the uredmial soi'i 2-celled, ellipsoid, 23-29 
by 42-48 [X, narrowed below, rounded or narrowed above, slightly or not constricted 
at the septum; wall pale lemon-yellow, uniformly thin, 1-1.5//, smooth, the pores 
one in each cell near the septum; pedicel colorless, evenly thick, 5-7 ^x, once to twice 
length of spore. 
On Juniperaceae: 
Chamaecyparis nootkatensis (Lamb.) Spach, Oregon, Alaska. 
Distribution: From southeastern Alaska to northwestern Oregon, in cool 
localities upon the sea coast northward or 5,000-6,000 feet elevation southward. 
