LICHENS 
III 
the following addition : L. occulata gonatodcs Ach., on rock on St. 
Paul Island. Of another plant he notes : ’''•Lecanora saxicola Schaer. 
—Specimens which may prove to represent a new species have been 
provisionally referred here by Mr. Branth.” 
PLACODIUM. 
KEY TO THE SPECIES. 
Thallus well developed, typically lobed at the circumference. 
Thallus orange-colored... elegans. 
Thallus bright yellow. ... murorum . 
Thallus poorly, or not at all, developed, not lobed at the circumference. 
Spores simply bilocular. 
Thallus orbicular, crenate-granulose..... crenulatum. 
Thallus effuse, granules usually crowded into heaps, sometimes 
scattered. vitellinum. 
Spores polar-bilocular. 
Growing over mosses. jungermannice. 
Growing on wood or stone. 
Thallus very uneven, warted. aurantiacutn. 
Thallus comparatively smooth. 
Hypothallus binish-black...... cerinum. 
Hwpothallus obsolete. 
Apothecia orange-colored beneath and on the margin. 
cerinum. 
Apothecia greenish beneath and on the margin. 
fuscoatra. 
120. Placodium vitellinum (Ehrh.) Naeg. & Hepp. 
Lichen vilellinus Ehrhart, Crypt, n. 155. 1785. 
Placodium vitellmum Naegeli & Hepp, Sporen der Flecht. Eur. n. 70. 1853. 
•— Sowerby, Eng. Bot. t. 1792. 
Hot Springs, Baranof Island (Trelease, 963 in part). On rocks 
with Lecidea enteroleuca and Parmelia saxatilis. Wright collected 
this species at Bering Strait, while Rothrock reports it from Port 
Clarence. Under the synonym Leca?tora vitellina Ach., Nylander 
reports its occurrence on St. Lawrence Island. 
It is a widely distributed species and closely related to the following, 
which may, perhaps, be considered as developed from it. 
121. Placodium crenulatum (Wahl.) Tuck. 
Lichen murorum y crenulatus Wahlenberg, Lapp. 416. 1812. 
Placodium crenulatum Tuckerman, Syn. N. A. L. 1: 180. 1882. 
Hot Springs, Baranof Island (Trelease, 9S4) ; Plover Bay, Siberia 
(Trelease, 995, 996). On stones. In Rothrock’s list this is reported 
