FINK—THE LICHENS OF MINNESOTA. 247 
2. Staurothele diffractella (Nyl.) Tuck. Gen. Lich. 258. 1872. 
Verrucaria diffractella Nyl. Mém. Soc. Acad. Maine et Loire. 4: 33. 1858. 
Thallus ashy,varying toward pale yellowish or olivaceous-brown, chinky-areolate 
(diffract), widely spread over the substratum as a continuous or more or less broken 
crust; apothecia immersed in protuberant areoles of the thallus, minute and indicated 
by the ostiole and surrounding minute darkened area, the perithecium dark brown or 
blackish brown, the amphithecium pale; paraphyses becoming gelatinized and coher- 
ent; asci clavate or variously irregular; spores ellipsoid, hyaline, muriform, but cells 
far less numerous than in the last, sometimes slightly colored, 15 to 22 » long and 9 to 
12” wide, eight in each ascus. 
Whole external appearance much as in the species above. 
Collected at New Ulm and Granite Falls. On various rocks. 
A North American lichen known elsewhere in Vermont, Massachusetts, Alabama, 
Illinois, lowa, and Missouri. 
\ 
Family LEPRARIACEAE. 
AMPHILOMA I'r.; Koerb. Syst. Lich. 110. 1855, 
The thallus is very rudimentary, consisting of a tangled mass of fungal hyphe, 
which are closely mingled with the algal celle. It is evidently devoid of cortical layers 
and not differentiated internally into medullary and algal layers. The whole structure 
is soredioid in nature and appears asa whitish, mealy orat least friable growth, confined 
to moist habitats. Clustered, downward-extending, dark bundles of hyphze form the 
rhizoids. The alge are at least closely related to Cystococcus humicola. The existence 
of apothecia is to be doubted. 
Our only species has been placed with the genus Pannaria, without any apparent 
reason. While there is certainly a lichen in the making, not enough is known of 
the fungal symbiont to warrant any definite statement as to relationship. Our com- 
mon Pleurococcus vulgaris of trees and rocks in moist places is almost always associated 
with fungal hyphe, and the closely associated algee and fungi may spread about over 
the substratum and appear quite like a rudimentary lichen thallus. This associa- 
tion is nearer to the present lichen genus than any other structure known to the writer, 
A single species occurs on our trees or rocks or rarely on earth in moist places. 
Type species Amphiloma elegans (Link.) Fr. loc. cit. But this our Placodium 
elegans, and the genus Amphiloma, is invalid and must be abandoned in the revision 
of lichen genera. 
Amphiloma lanuginosum (Hoffm.) Nyl. Act. Soe. Linn, Bord, 21: 315, 1896, 
Puate 51. 
Lichen lanuginosus Hoffm. Enum. Lich. Icon. 172. 1784. 
Thallus closely adnate, granulose; orbicular and with plain lobation at the circum- 
ference or widely spread over the substratum and irregular in form and without lobing, 
when orbicular about 25 to 65 mm. in diameter, sea-green varying toward whitish or 
very rarely toward a pale sulphur-color, said to have a thin blue-black hypothallus; 
apothecia hardly known. 
Widely distributed in the State. On rocks and bases of trees, rarely on earth in 
moist places. 
Common enough in the United States east of the Rocky Mountains and northward 
throughout eastern British America and also in Alaska. Known in all of the grand 
divisions. 
Pannaria lanuginosa of the preliminary reports. 
EXPLANATION OF PLATE 51 —Plant, scattered where exposed, but forming a continuous crust where 
shaded by a fallen log. About one-sixteenth natural size. 
