150 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
1. Heppia despreauxii (Mont.) Tuck. Gen. Lich. 46, 1872. 
Solorina despreauxii Mont. in Webb & Berth. Hist. Nat. Canar, 32: 104. 1840. 
Thallus foliose or possibly to be considered squamulose, closely attached to the 
substratum by numerous rhizoids, orbicular with the edges sometimes raised and 
crenately lobed, very small, 1.5 to 4 mm. or possibly reaching 6 mm. in diameter, 
or frequently the thalli clustered into a continuous crust covering an area 20 to 30 
mm. in diameter, smooth above or frequently somewhat rugulose, olive in color, 
varying toward green or black, usually pale below; apothecia frequently solitary in the 
small thalli, commonly immersed and depressed-urceolate, rarely even convex, the 
disk reddish brown, small or becoming larger and occupying nearly the whole thallus, 
0.75 to 2.5 mm. in diameter; hypothecium pale to pale yellowish; hymenium pale 
below and yellowish above; paraphyses somewhat coherent, commonly simple, fre- 
quently thickened and brownish toward the apex; asci clavate to cylindrical; spores 
hyaline, oblong-ellipsoid, 17 to 26 » long and 7 to 10 pe wide. 
Collected on calcareous soil in widely separated portions of the State, No doubt 
occurring wherever such soil exists in Minnesota. 
Widely distributed in the United States, but I do not find it recorded from British 
America. SHHeppia virescens (Despr.) Nyl., reported for North America, is the same, 
and probably also Heppia terrena Nyl. from California. Known also in Europe and 
Africa. 
PANNARIA Del. in Bory, Dict. Class. Hist. Nat. 13: 20. 1828. 
The thallus may be distinctly foliose, though more often small and squamulose. 
It is usually quite closely attached to the substratum by means of rhizoids, though 
often resting upon a more or less distinct hypothallus. Indeed, it is in the present 
genus that the so-called hypothallus finds its best expression. The thallus appears 
to be crustose in some species, but so far as we have examined there is more or less 
of a cellular cortex below as well as above. This is true of the Minnesota species at 
least. The upper cortex is well developed, thick, the cells large and distinct. The 
medullary and algal layers are distinct in the more strictly foliose forms, but in those 
approaching a squamulose condition there appears to be a parenchymatous structure 
throughout and algal cells scattered throughout, except in the outer cells of the cortex. 
In all of ours, the algal symbiont is a blue-green alga, probably Polycoccus, and the 
chains of cells can usually be seen readily enough. In color the thallus varies from 
sea-green to a dull black. 
The apothecia are usually small and sessile or subsessile upon the thallus. The 
thalloid margin may be present or absent, sometimes even in a given species. The 
disk is usually more or less concave and varies in color from a reddish brown to a 
dull black. The hypothecium and the hymenium vary from pale to brown. The 
asci vary from clavate to cylindrical in form, and the pale or hyaline spores from 
simple to 4-celled. 
Tuckerman has included in the genus forms having green algal cells, others having 
both green and blue-green, and others having blue-green only. Doubtless his genus 
Pannaria should be divided into at least four genera, However, excluding Am- 
philoma, all of our Minnesota species are forms having the blue-green algal cells. 
There is still a difficulty as to spore characters, but simple and 2-celled spores occur in 
one species and 2 and 4-celled spores in two others, so that a division on this basis 
alone would be somewhat arbitrary. On the other hand, the last three species pres- 
ent certain differences in thallus structure, and we may be committing a serious 
error in not recognizing the genus Lecothecium of Trevisan. 
The genus is related somewhat closely to Collema and less closely to Heppiaand 
Peltigera. 
Seven forms occur in Minnesota. On trees, rocks, or earth. 
Type species Pannaria rubiginosa (Thunb.) Del. loc. cit. 
