FINK—THE LICHENS OF MINNESOTA. 145 
whole, these algal symbionts seem to be a form of Gloeocapsa, In some species found 
in North America and referred to the present genus the algal cells occur in chains. 
These we have not studied carefully, but they should perhaps be referred to another 
genus. The thallus as a whole may be merely an irregular or even somewhat rounded 
mass, or it may be somewhat or even decidedly branched. The color is usually a dull 
black, and the thallus reminds one somewhat of that of certain Collemas. 
The apothecia are very small, subglobose and immersed, or more rarely becoming 
superficial and more or less disk-shaped. They are either terminal on the lobes or 
variously scattered over the thallus. The hypothecium and the hymenium vary 
from colorless to brown. The paraphyses are more or less coherent and indistinct, but 
seem to be uniformly simple. In the material examined, the asci scarcely showed 
apical thickening. In the species admitted here, the spores are hyaline and are 
simple, though plants having 2-celled spores have usually been admitted to the genus, 
Notwithstanding the peculiarity of the present genus as regards the algal symbiont, 
it shows an apparently close relationship with Senechoblastus and a somewhat more 
remote one, when the spores are considered, with Collema. Yet, doubtless, all con- 
sidered, the relationship is closer with Pyrenopsis or Lichnia. 
Three species have been determined from the rocks of the State. Other sterile 
forms have been collected. 
Type species Omphalaria nummularia (Dut.) Dur. & Mont. loc. cit. 
KEY TO THE SPECIES. 
Thallus scarcely or only slightly lobed; plants small......----- 1. O. minnesotensis. 
Thallus plainly lobed; plants larger. 
Lobes strongly ascendant. ........--------+--------------- 2. O. pulvinata. 
Lobes shorter and only slightly raised...............------- 3. O. phyllisca. 
1. Omphalaria minnesotensis sp. nov. 
Thallus adnate or somewhat raised from the substratum, irregular in form or rarely 
rounded, very small, 0.5 to 2 mm. in diameter, above smooth or more commonly un- 
even; lobes absent or short and irregular, black and rigid; algal cells in clusters; 
apothecia immersed and minute, scarcely exceeding 0.3 to 0.5 mm. in diameter, 
globose with a punctiform disk, often in plainly raised pustules, one to several in each 
plant; hypothecium pale or slightly colored; hymenium pale; paraphyses more or 
less coherent, gelatinous and indistinct; asci cylindrico-clavate and variously irregular; 
spores minute and numerous in each ascus, subspherical to ellipsoid, 3 to 6 » long 
and 2 to 3 » wide. 
On calcareous rocks at Minneapolis. 
2. Omphalaria pulvinata (Schaer.) Nyl. Ach. Soc. Linn. Bord. 21: 265, 1856. 
Collema stygium pulvinatum Schaer. Enum. Lich. Eur. 260. 1850. 
Thallus pulvinately lobed, the lobes ascendant or suberect, giving the thallus a 
fruticose tendency, but also with a basal horizontal and strictly foliose portion, 
predominating in younger and less developed states and giving character to the 
whole structure; black in color, the lobes more or less divided and having variously 
irregular margins; apothecia minute, scarcely exceeding 0.6 mm. in diameter, some- 
times becoming prominent and tuberculate, said to be pallescent (Nylander), though 
this has not been observed in ours, more commonly along the margins of the lobes; 
hypothecium pale or pale brownish; hymenium pale below and pale brownish above; 
paraphyses simple, more or less gelatinized and coherent; asci clavate; spores short- 
ellipsoid, 9 to 12 » long and 5 to 7 » wide. 
Collected once in the State. On calcareous rocks at Mankato. 
Previously known from New England, New York, Iowa, Nebraska, and Colorado. 
But Tuckerman seems not to have seen the apothecia, which are common enough in 
ours and in the Iowa plant. Known also in Europe and Africa, 
