220 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
It is by no means plain that the present family is highest as regards thallus struc- 
ture or development of the apothecia, but it is when we consider these elements in 
connection with the spore characters that the position of the family becomes apparent. 
We have the muriform spore in the Gyrophoraceae, the Lecideaceae, and the Gra- 
phidaceae as well as here, but always in connection with lower types of structure 
of thallus or apothecia, or both. 
The relationships of the family with the Parmeliaceae and the Teloschistaceae 
have been given in the descriptions of those families, and it need only be added 
here that in admitting Urceolaria to the present family we have established a some- 
what close relationship with the Gyalectaceae, through Urceolaria and Conotrema. 
The first two genera of the family are well represented in our flora, but our members 
of the family as a whole are not very numerous. The thallus structure shows about 
the same amount of variation as is found in the last family, and the relationship of 
the apothecia to the thallus is about the same as in the Parmeliaceae. But the spores 
are always brown and vary from 2-celled to muriform conditions. 
RINODINA <Ach.; 8S. F. Gray, Nat. Arr. Brit. Pl. 1: 448. 1821. 
The thallus is crustose, though in a few species herein admitted to the genus there 
is more or less of lobing at the circumference. The structure is closely adnate, 
usually areolate, and is attached to the substratum by commonly dark hyphal rhi- 
zoids. In the lobed forms, there is more or less of an upper pseudocortex of hyphe, 
but in the lower more strictly crustose species, the cortex is absent, or rather repre- 
sented by a bending and branching of the hyphe near the upper surface, to form the 
poorly developed protective layer so common in crustose thalli. The algal sym- 
bionts are commonly Cystococcus, though they vary considerably in size in the 
different species, and in some species having larger and more irregular alge, Pleuro- 
coccus may replace the usual Cystococcus. The common colors of the thalli are sea- 
green, ashy, straw-color, and yellowish. 
The apothecia are commonly small or minute, and may be immersed, adnate, or 
sessile. Indeed, all of the above dispositions of apothecia may occur in a single 
species. The exciple is thalloid, but in a majority of the species this structure may 
disappear entirely. The disk is commonly flat and its color usually black or brown- 
ish black. The hypothecium is commonly pale, though sometimes brownish. The 
paraphyses are simple or rather rarely branched. The spores are brown and 2-celled. 
The present genus is doubtless to be regarded as intermediate between Physcia 
and Buellia, lower than the former and on the whole higher than the latter. The 
thalli of the best developed Rinodinas seem quite as high as those of the lowest 
Physcias, while some of the lower members of the present genus show thalli scarcely 
better developed than those of some of the Buellias. The thalli and the apothecia 
of the Rinodinas also resemble those of Lecanoras and Placodiums, but the spores 
indicate a much closer relationship with the two genera named above. Finally, 
the tendency of the thalloid exciple to disappear looks toward Buellia. Possibly 
our Rinodina oreina should be excluded from the genus, but the thallus is after all 
essentially crustose. 
Ten forms occur in the State. On trees and rocks. 
Type species Rinodina atra (Huds.) 8. F. Gray, loc. cit. But this is Lecanora 
atra, and the generic name Rinodina will doubtless have to be abandoned eventually. 
KEY TO THE SPECIES. 
Confined to rocks. 
Thallus blackish, of flat or concave areoles............-.-- 6. R. nigra, 
Thailus lighter-colored. 
Thallus granulose, becoming chinky, scurfy or sub- 
areolate, whitish, sea-green or brownish. ..-........- 4. R. bischoffit. 
