FINK—THE LICHENS OF MINNESOTA. - 233 
muriform spores in the present family, but it has seemed better to place this genus in 
a higher position with the Endocarpaceae. 
The thalli of the Verrucariaceae are surely better developed than those of the 
Pyrenulaceae, those of the former family being usually in part or largely above the 
substratum and verrucose or areolate, while those of the latter family are usually 
wholly or largely within the substratum and very rudimentary and inconspicuous. 
The relationship of the Verrucariaceae to the Pyrenulaceae is certainly a very close 
one and, indeed, the older lichenists were in the habit of placing all the members of 
the two families in a single genus. However, it seems that the difference in char- 
acter of thallus and spores, and more especially of the paraphyses, furnishes some 
ground for the separation into two families. Yet it is by no means clear that we 
have pursued the best plan in following some of the European lichenists into this 
subdivision. 
It must be further stated that the present family is somewhat closely related to the 
Gyalectaceae through Conotrema and to the Physciaceae through Urceolaria. Prob- 
ably the Pertusariasare more closely related to the Arthopyrenias and Pyrenulas than 
to the Verrucarias. 
VERRUCARIA Scop. Intr. Hist. Nat. 61. 1777. 
The thallus is crustose, on the whole not so rudimentary as that of Sagedia, Artho- 
pyrenia, or Pyrenula, more conspicuous upon the substratum or more or less hypo- 
lithic, and never entirely disappearing, at least not in any of our species or others 
examined. In some of the species the thallus is quite smooth, but it is more com- 
monly verrucose or areolate and usually widely spread over the substratum. The 
thallus color varies greatly, both white and black thalli and various intermediate 
colors occurring within the genus. Schneider@ finds Pleurococcus constantly present 
as the algal symbiont in all the species examined by him. 
The apothecia are small or minute and are more or less immersed in the thallus and 
substratum. They are commonly globose, and the perithecium is black (brownish- 
black in section). The amphithecium is pale or finally more or less colored. The 
paraphyses are short and soon become gelatinized and coherent-indistinct. The asci 
also commonly become more or less gelatinized. The spores are simple in all mem- 
bers of the genus as defined by Schneider, though Tuckerman and Nylander both 
admitted, to the genus lichens having quite various spore characters. Evidently 
the view of the latter must be revised, and we may follow that of Schneider. 
The genus is somewhat closely related to Arthopyrenia and Pyrenula, but when 
the differences in spore characters, thallus development, and algal symbionts are 
considered, there seems at least to be no sufficient reason for placing the two genera 
together as has frequently been done. 
Five species and subspecies occur in the State. On various rocks. 
Type species Lichen ericetorum L. Sp. Pl. 1141. 1753. But this plant is, according 
to Wainio,® identical with our Jemadophila aeruginosa. This makes the name Verru- 
caria invalid and subject to change in the revision of lichen genera, 
KEY TO THE SPECIES. 
On earth: thallus thin, ashy or greenish, granulose, often disap- 
pearing...........2.2 220.000.202.222 2222 eee eee eee 1. V. epigaea. 
On rocks. 
Thallus usually whitish; smooth and chinky, or scurfy or 
granulose.............--02-02-022 202222 eee eee eee eee 2. V. muralis. 
a Textb. Lich. 185. b Act. Soc. Faun, Flor. Fenn. 14: 20. 1888, 
7920—10——16 
