242 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
1. Thelocarpon prasinellum Ny!. Flora 64: 451. 1881. 
Thallus a thin crust over the substratum, greenish in color and commonly disap- 
pearing, all but the greenish hemispherical veils surrounding and concealing the 
minute and scattered apothecia; apothecia with thalloid veil scarcely exceeding 
0.1 to 0.2 mm. in diameter, and scarcely noticeable except when brightened after 
rain, the amphithecium pale; paraphyses slender and considerably branched, and 
without apical thickening or color; asci cylindrical, ellipsoid, or becoming distended 
and variously irregular; spores oblong-ellipsoid, numerous in the asci, 4 to 7 » long and 
2.5 to 4 wide. 
Generally distributed over the State. On old pine wood and rarely on rocks. 
Easily passed over for Pleurococcus, or for Acolium in a rudimentary condition, but 
the hand lens reveals the deception. 
Known elsewhere in North America in New Bedford, Massachusetts, and in a 
number of localities in Iowa. No doubt a common lichen, at least throughout a large 
portion of North America, but overlooked. Known also in Europe. 
DERMATOCARPON Fr. Syst. Orb. Veg. 259. 1825, 
The thallus is for the most part plainly foliose with the lobes rising more or less from 
the substratum, but in some of the smaller species the thallus is smaller and the whole 
structure closely adnate as in Endocarpon. It is thick and rigid and in the higher 
and more plainly foliose species is attached by an umbilicus, these larger thalli 
reminding one of forms of Umbilicaria. Upper and lower cortices are present, and 
in the larger species the lower cortex is better developed for support, here again 
recalling Umbilicaria. Within the upper and lower cortices are well developed 
algal and medullary layers, The algal symbiont is similar to that of Endocarpon, 
but is somewhat larger. In color the thalli vary from ashy and gray to brownish or 
even a dark brown. 
The apothecia are immersed in the thallus and are indicated at the upper surface 
by numerous minute pores, which appear as spots upon the surface. As in Endo- 
carpon, the perithecium is scarcely developed, and the amphithecium is usually pale 
in section. The paraphyses gelatinize with age and become coherent. The spores 
are simple. 
As to spore characters, Dermatocarpon is more closely related to Verrucaria, but 
the thallus structure is more like that of Endocarpon, this last genus in this respect 
being intermediate between the other two. 
live species and subspecies have been found within the State. On rocks, trees and 
earth. 
Type species Dermatocarpon miniatum (L.) Fr. loe. cit. 
KEY TO THE SPECIES. 
Never on rocks; small plants, closely adnate, 
On trees, margin sometimes slightly raised.....2..2..-. 2. D. arboreum. 
On earth, margin not raised........................... . D. hepaticum. 
On rocks; larger plants, loosely attached by an umbilicus. 
Thallus large, entire or somewhat lobed, ashy to olive- 
brown...----.-. 22222222 
Thallus deeply divided into smaller lobes. 
Lobes extending almost to the umbilicus, closely 
imbricated, of same color as the above.......... la. D. miniatum compli- 
catum., 
wo NO 
— 
. D, miniatum. 
Lobes less imbricated, thinner, darker-colored; on 
rocks frequently wet.......................-.. Ib. D. miniatum aquati- 
cum. 
