FINK—THE LICHENS OF MINNESOTA, 931 
to 1.5 mm. in diameter, the disk commonly convex and black but rarely white- 
pruinose, the thalloid margin only noticeable in the early development, the margin 
later becoming blackened and the whole apothecium having an external lecideoid 
appearance; hypothecium more or less cellular, brown or blackish-brown; hymenium 
pale-brownish; paraphyses simple or rarely branched, thickened and brownish toward 
the apex; asci clavate; spores brown, 2-celled, oblong to ellipsoid, 17 to 28 » long and 
7 to 10 » wide. 
Widely distributed in the State, but not common in any portion. On trees and 
rarely on rocks. 
Well known in North America, except in the extreme north and west. Distributed 
throughout the grand divisions. 
EXPLANATION OF PLATE 48.—Plant on white cedar bark, showing the sorediate thallus. Natural size. 
URCEOLARIA Ach. Lich. Suec. 1, 30, 258. 1798. 
The thallus is strictly crustose and commonly becomes quite thick. The surface is 
usually distinctly areolate or verrucose, the areoles or verrucee often becoming quite 
convex and prominent. There is what may be regarded as a poorly developed upper 
pseudocortex of entangled hypha, and below this the algal and medullary layers are 
somewhat differentiated. There is no showing of a lower cortex; hyphal rhizoids are 
quite numerous as attaching organs. The alge are a form of Cystococcus, the cells 
often occurring solitary instead of being united in larger or smaller groups as is the 
more common condition of Cystococcus cells in lichen thalli. Sea-green, ashy and 
whitish are the common colors of the thallus. 
The apothecia are commonly small or minute, but may reach middle-size in some 
of the species, They are more commonly scattered and 1, 2, or 3, in each areole, but 
sometimes they become more numerous with several to each areole. They are com- 
monly immersed in the thallus, and the disk is more or less urceolate. There is a 
usually dark exciple and hypothecium, and surrounding the proper exciple almost 
always a thalloid one. The hymenium is pale or brownish. The paraphyses are 
simple or rarely branched. The spores are muriformly many-celled and become 
brown when mature, the brown spores commonly being smaller and doubtless past. 
their prime. 
The relationships of the genus are so obscure as to make any arrangement appear 
somewhat artificial and subject to criticism. The apothecium is in the main open, 
though in some of the species there is certainly an approach to the true perithecium, 
The spores are clearly nearest to those of Rhizocarpon or Staurothele, and the dark 
exciple and hypothecium look in the same direction. However, the thallus and the 
usual presence of a thalloid exciple seem to bring the Urceolarias near to the Rinodinas 
or the Lecanoras. On the whole it has appeared best to place the genus nearer to 
Rinodina. 
Tuckerman admits two North American species, both of which have been met in 
the State. On rocks, and rarely on earth and old wood. 
Type species Urceolaria agelea. Ach. loc. cit. This plant has been placed under 
Phlyctis Wallr. by the best European lichenists and surely falls outside the present 
conception of Urceolaria, which should replace Phlyctis. 
KEY TO THE SPECIES. 
Proper exciple denticulate.........--------+-+----------------- 1. U. scruposa: 
Proper exciple radiate-striate..-.-.-.---------------------+-- 2. U. actinostoma. 
1. Urceolaria scruposa (Schreb.) Ach. Lich. Suec. 32, 258. 1798. Ficure 16, 
Lichen scruposus Schreb. Spic. Fl. Lips. 183. 1771, 
Thallus suborbicular and occurring in medium-sized or large patches, 4 to 15 cm. 
across, or irregular and variously spread over the substratum, thickened and verru- 
