160 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Lower surface of the thallus whitish. 
Thallus middle-sized. 
Rhizoids moderately developed......... 8. P. canina. 
Rhizoids numerous and forming a spongy 
Nap. .....2 222. eee eee 8a. P. canina spong- 
iosa, 
Thallus smaller or thinner, 
Thallus thinner but expanded. .......... 8d. I. canina leucor- 
rhiza. 
Thallus smaller. 
Thallus scarcely rhizoid-bearing, but 
sorediate. 2. .......000......2.. 8c. P. canina sored- 
tata. 
Thallus scarcely rhizoid-bearing, not 
sorediate. .........220-0..0.....2 8b. P. canina spuria. 
1. Peltigera aphthosa (L.) Willd. Fl. Berol. Prodr. 347. 1787. PLatEs 29, 30. 
Lichen aphthosus L. Sp. Pl. 1148, 1753.4 
Thallus somewhat closely attached to the substratum, with the margins or the 
entire lobes more or less ascending, middle-sized to large, 6 to 20 cm. in diameter, 
sprinkled more or less with the small and irregular cephalodia, smooth above and 
devoid of trichomatic hyph, except those lying below and closely adhering to the 
cephalodia to hold them in place, the lobes broad and rounded and sometimes more 
or less imbricated, the margins subentire or more commonly somewhat crisped and 
variously irregular; from apple-green to sea-green or rarely even brownish, below 
white and rarely white-veined, but the veins more commonly dark and even the 
whole surface becoming so, the veins clothed with delicate rhizoids, these composing 
a close nap, the surface also bearing scattered larger rhizoids; apothecia on somewhat 
extended lobules, middle-sized or larger, 4 to 8.5 mm. in diameter, ascendant, fre- 
quently becoming revolute or convolute, often superficial, the margin entire or 
crenulate, the disk reddish brown; hypothecium brownish; hymenium pale or brown- 
ish below and darker above; paraphyses simple or rarely branched, commonly thick- 
ened and brownish toward the apex; asci cylindrico-clavate; spores acicular, color- 
less or showing pale brownish in the asci, 4 to 8-celled, 45 to 75 » long and 4 to 7 It 
wide. 
Generally distributed over the northern portion of the State. On earth and fre- 
quently on humus-covered rocks. 
Distributed much as the next in North America, but extending southward, at least 
in the mountains. Also known in Europe and Asia. 
EXPLANATION OF PLATE 30.—Plant on earth, showing the ascending thallus lobes dotted over with 
cephalodia. Natural size. 
2. Peltigera venosa (L.) Hoffm. Deutsch. Fl. 2: 107. 1795. 
Lichen venosus L. Sp. Pl. 1148. 1753. 
Thallus usually composed of scattered lobes, each of which may be regarded as a 
plant, or rarely more or less connected into a larger thallus, the single or more rarely 
united lobes somewhat ascending, commonly more or less fan-shaped or in the form 
of an isosceles triangle, smooth and devoid of trichomatic hyphee above, sea-green 
varying toward ashy or brownish, the margins of the nonfertile lobes entire or some= 
