186 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
ordinary Cystococcus. In most of the species soredia occur scattered over the upper 
surface of the thallus. Shades of sea-green and yellow are the prevailing colors of the 
thalli. 
The apothecia are of medium size or larger and are either sessile or adnate. The 
exciple shows much the same structure as the upper cortex and is thus scarcely so 
well developed as that of the Lecanoras. The alge of the exciple are not numerous, 
and the whole structure appears to be somewhat biatoroid. Indeed, the exciple may 
disappear entirely, leaving the apothecium strictly biatoroid. The hypothecium is 
pale. The paraphyses are slender, and commonly simple, though branched forms 
may be looked for in all of the species. The spores are long and acicular, hyaline, 
variously curved, and 4 to several-celled. 
The relations of the genus are not difficult to trace. As to the structure of the 
thallus and the apothecia the resemblance to a majority of the Lecanoras is apparent 
enough. When we turn to the spores, we note a similarity to those of the Bacidias. 
The thallus also is only a little higher in development than that of the Bacidias, while 
the poorly developed thalloid exciple points to a more or less close relationship with 
the same genus. On the whole, it may well be doubted whether the present genus 
is more closely related to Lecanora than to Bacidia. 
Only a few species of the genus are known in North America, and of these only one 
has been noted in Minnesota. 
Type species Haematomma vulgare Mass. loc. cit. 
1. Haematomma elatinum (Ach.) Koerb. Syst. Lich, 153, 1855. 
Lecanora elatina Ach. Lich. Univ. 387. 1810. 
Thallus crustose and thin, smooth and somewhat chinky or more commonly becom- 
ing densely granulate or powdery, ashy-white or faintly yellowish, closely adnate 
and attached by hyphal rhizoids, in the less powdery conditions an upper pseudo- 
cortex distinguishable as a thin structureless and gelatinized mass or faintly showing 
coherent hyphe; apothecia small to middle-sized, 0.5 to 1.5 mm. in diameter, sessile, 
the disk commonly flat or finally convex, and from light brownish to dark reddish 
brown, frequently somewhat pruinose, the thalloid exciple irregular and evanescent, 
leaving the apothecium strictly biatoroid; hypothecium pale; hymenium of the 
same color or darker above; paraphyses simple or rarely branched toward the com- 
monly thickened and somewhat colored apex; asci clavate or cylindrico-clavate; 
spores fusiform-acicular, curved, 4 to 6-celled, 38 to 58 » long and 4 to 6 » wide. 
A single collection has been made, at Tofte. On trees. 
Found in New England, New York, North Carolina, and northward throughout 
British America. Known also in Europe and Asia. Perhaps more widely distrib- 
uted, but the synonymy is uncertain. 
Lecanora elatina of the preliminary reports. 
Family PERTUSARIACEAE. 
In the Pertusariaceae we have a family which is extremely troublesome, though 
composed of a single genus. We have followed Zahlbruckner in recognizing the 
family, but have not seen our way to follow him in separating the large-spored Lecano- 
ras, L. tartarea and L. pallescens, under the generic name Ochrolechia, and placing 
them in the present family. It is true, however, that certain members of the present 
family tend toward the open condition of apothecium and seem very closely related 
to these Lecanoras. We have recognized this close relationship in placing the Per- 
tusariaceae next after the Lecanoraceae. 
On the other hand, the apothecia more commonly open by an apical pore, and 
Schneider has seen fit to place the genus Pertusaria with the Verrucariaceae without 
recognizing the family Pertusariaceae at all. And his position is not without strong 
