(128 ) 
The typical difference in the spores separates this genus from the 
other groups of Hulecanorei: and its relation to the centre (Lecanora 
§ Eulecanora) is much that of Physcia to Parmelia; and to Placodium, 
much that of Physcia to Theloschistes. As presented in the great major- 
ity of species, the differentiation of the spore does not advance beyond 
the bilocular stage, which is commonly assumed to express the spore- 
character of the group: but R. Conradi, Koerb. Syst. p. 128, as well as 
Lecan. pyreniospora, Nyl. Scand. p. 151, f. 6, offer the quadrilocular; and 
L. diplinthia, Nyl. (in Prodr. Fl. Gran. 1.c¢. p. 31) as described (‘ sp. fusce 
ellipsoidee seriebus 4-loculose, scilicet loculis 2 apicalibus simplicibus, et 
seriebus 2 mediis singulis e loculis 2 constitutis, vel interdum e loculis 3’) 
the sub-muriform-plurilocular gradation. This last modification charac- 
terizes also R. sabulosa, Tuckerm. Lich. Calif.; R. Carestie, Bagl., cit. 
Arn.; and BR. Lusitanica of the latter author (Flora, 1868, p. 244) who 
calls the spores of his lichen ‘fast parenchymatischen.’ It thus suffi- 
ciently appears that though far less fully exhibited than in Buellia, as 
here taken, the whole differentiation of the brown spore is indicated in 
Rinodina ; which thus prefigures our conception of Buellia. The for the 
most part granulose thallus is modified here just as in Placodiwm and 
Lecanora; passing into squamulose, and finally into radious, and some- 
what lobed conditions (sect. Dimelena, Stizenb.). 
Of the twenty odd best-marked forms described, more than two-thirds 
are northern, and nearly as large a proportion (due doubtless to fuller 
study) European; but scarcely half have been recognized as yet in North 
America. 
Of the effigurate section (Dimelena) we possess all the northern spe- 
cies. KR. nimbosa (Fr. Diploicia, Mass., Koerb.) is confined as yet to 
Greenland (Vahl, e Th. Fr. l. ¢. p. 95) but may well occur, in alpine dis- 
tricts, southward of this limit.——R. oreina (Ach.) Mass., which is com- 
mon in the northern States, extends southward, along the mountains 
(North Carolina, Rev. M. A. Curtis; Tennessee, Mr. Ravenel) and is 
found also in the Rocky Mountains (Dr. Hayden) and in California (Mr. 
Bolander).——R. chrysomelena (Ach.) has perhaps mainly a southern 
range, having only occurred once (on granite boulders, New Bedford, 
Mass., Mr. Willey) north of Pennsylvania (Hornblende rocks, Chester co., 
Dr. Michener) where Muhlenberg probably discovered it; but extending 
southward to Georgia (Mr. Ravenel).——Of the granulose section (Huri- 
nodina, Stizenb.) R. sophodes is the familiar type, and may well embrace, 
as in Nylander’s view, a considerable number of forms which pass for 
species with other writers. Several of these tend to squamulose luxuri- 
ance, as R. Zwackhiana, Krempelh., of the Bavarian alps; and Lecanora 
tephraspis, Tuckerm. Suppl. 1, 1. c. p. 425 (from rocks inundated most of 
the year, at Brattleboro’, Vermont, Messrs. Russell and Frost) is another, 
exhibiting similar features. These are not however wholly wanting in 
the varied modifications of R. sophodes, v. confragosa, Nyl.; to which may. 
