FINK—THE LICHENS OF MINNESOTA. 65 
spores are doubtless somewhat closely related with the Physciaceae, especially 
Buellia with Rinodina and Rhizocarpon with Urceolaria. 
BIATORELLA De Not. Giorn. Bot. Ital. 2': 192. 1846. 
The thallus is crustose and commonly granulose, sometimes verrucose or subareo- 
late, and is on the whole much less developed than in Lecidea. Indeed, it is quite 
commonly evanescent or so rudimentary as to appear only with the most careful 
examination with lens or even in section with microscope. Of course there is no 
cortex, nor can algal and medullary layers be distinguished. The thin and rudimen- 
tary structure lies mainly above the substratum to which it is attached by hyphal 
rhizoids. The algal cells seem to be Cystococcus, 
The apothecia are commonly minute or at least small, though they may reach 
middle size in one of our species. The exciple is of the lecideoid type, composed of 
closely interwoven hyphe, and is frequently evanescent. It is usually light in color, 
but may be darker and firm as in the higher members of Lecidea. The disk may 
be flat or convex and in the latter condition frequently overgrows the exciple, The 
exciple, however, may be persistent and raised somewhat above the border of the 
disk. Both hypothecium and hymenium vary from pale to brown, The spores are 
minute and numerous in the asci, though in one species not represented in our flora 
there are only 12 to 18 spores in each ascus. They are simple and are globular to 
oblong or ellipsoid in form. 
The present genus is closely related to Lecidea, though possibly nearer Bacidia 
or Bilimbia, as the minute and numerous spores may have arisen from a breaking up 
of the long compound spores of members of these genera to form the minute and 
more numerous ones of the present genus. Tuckerman has included in Lecidea and 
Heterothecium forms having minute and numerous spores. We do not encounter 
these among our Minnesota species, but it is evident that they should all be brought 
together into one genus, or possibly two closely-related genera. We have also trans- 
ferred Lecanora privigna to the present genus under the older synonym Biatorella 
simplex. 
The genus has four species and subspecies in Minnesota. On trees and rocks. 
Type species Biatorella roussellii (Dur. & Mont.) De Not. loc. cit. 
KEY TO THE SPECIES. 
Spores spherical.............0.2.....2222-0-2----------- L. B. moriformis. 
Spores oblong-ellipsoid. 
Apothecia pruinose .....................-..-.-.- 2a. B. simplex pruinosa. 
Apothecia not pruinose. 
Apothecia small or minute, adnate. .......... 2. B. simpler. 
Apothecia middle-sized, loosely sessile or sub- 
stipitate .... 22.2.0... ee eee eee 3. B. clavus. 
1. Biatorella moriformis (Ach.) Th. Fr. Lich. Scand. 2: 401. 1874. 
Arthonia moriformis Ach. Syn. Meth. Lich. 5. 1814, 
Thallus composed of very minute granules, these commonly compacted into a 
thin, smooth, or more or less leprose or chinky crust, sea-green or more commonly 
whitish or rarely brownish, widely spread over the substratum or disappearing en- 
tirely; apothecia small or minute, 0.2 to 4 mm. in diameter, adnate, flat to slightly 
convex, pale brownish to brown and finally black; exciple evanescent or entirely 
absent; hypothecium pale; hymenium pale throughout or brownish above; para- 
physes commonly simple and somewhat enlarged and brownish above, somewhat 
gelatinized and indistinct; asci clavate or ventricose; spores spherical, very minute, 
1.5 to 2.5 » in diameter, numerous in the asci. 
