FINK—THE LICHENS OF MINNESOTA. 245 
well developed. The structure is composed of minute rounded or more or less irreg- 
ular squamules, which may be scattered and solitary upon the substratum, or more or 
less clustered. The thallus is closely attached to the substratum by rhizoids. The 
color usually resembles that of dirt, so that it is easily passed over. The algal sym- 
biont issomewhat different from the common Cystococcus and seems to be Pleurococcus. 
The apothecia are immersed in the thallus, usually one in each squamule, and are 
minute and indicated at the surface only by an irregular and obscure pore. The 
perithecium is scarcely developed, but the amphithecium is pale or more commonly 
becomes brown or brownish. The paraphyses are distinct while young and short, but 
soon become gelatinized and coherent with each other and with the likewise gelati- 
nized asci, so that the whole hymenial mass is involved. The spores are muriform, 
hyaline or brown, commonly fewer than eight in each ascus, Thecial algze, or alge 
within the apothecium, are a peculiarity of the genus. 
The present genus is closely related to Dermatocarpon, as apparent in the general 
resemblance of the apothecia and their disposition, in the similarity in the algal 
symbionts, and only less in the considerable similarity in thallus structure. Also 
there is a close relationship with Verrucaria, shown in the apothecial characters and 
in the nature of the algal symbiont, though there is some doubt regarding the algal 
symbiont of the latter. The close relationship to Staurothele is shown in the spores. 
A single species is found in the State. On rocks. 
Type species Endocarpon pusillum Hedw. loc. cit. 
KEY TO THE SPECIES. 
On calcareous rocks, thallus quite thick.....................---- L. EB. pusillum. 
On earth, thallus thinner and lighter-colored .................-- la. BE. pusillum 
garovaglit. 
1. Endocarpon pusillum Hedw. Descr. Musc. Frond. 2: 56. pl. 21. f. a. 1789. 
Thallus foliose-squamulose, closely adnate, the squamules scattered or clustered, 
minute, 0.2 to 1.5 mm. across, sometimes in the closely clustered conditions forming 
an areolate surface or becoming more or less imbricated; the smaller ones rounded but 
the larger variously irregular, rather thick, appearing dirty to the unaided eye, but 
usually more or less olivaceous-brown under the lens; apothecia minute, one to four or 
rarely more in each squamule, immersed and their position indicated by the pore, this 
occupying a somewhat raised spot, the perithecium scarcely developed, the amphi- 
thecium pale or turning brownish; paraphyses becoming coherent and indistinct; asci 
clavate; spores brownish or at first hyaline, muriform, oblong, commonly 2 in each 
ascus, 23 to 45 x long and 12 to 18 « wide. 
On calcareous rocks, especially surface pebbles, and found in the State wherever 
such pebbles occur. Collected in several places in southwestern Minnesota, at Minne- 
apolis, and in the Leaf Hills. 
Known throughout the United States east of the Rocky Mountains. Found also in 
Europe. 
la. Endocarpon pusillum garovaglii (Mont.) Fink. 
Verrucaria garovaglii Mont. Ann. Sci. Nat. Bot. IIT. 2: 59. 1849. 
Thallus thinner and lighter-colored, the squamules on the whole smaller, though 
the smallest ones are very obscure and difficult to see upon the earthy substratum. 
Same general distribution in the State as the last, but also collected at Tower. On 
earth, and possibly rarely on rocks. 
Elsewhere in North America at New Bedford, Massachusetts, and in Illinois and 
Iowa. Known also in Europe and Africa. 
