(8) 
fructification of which was unknown, is in fact only of subordinate value 
as respects the system, and of possible occurrence within the natural 
limits of several genera. Thus D. flammea, Ach. (Cape of Good Hope, 
Herb. Sonder) is inseparable from Theloschistes ; D. ryssolea, Ach., is, 
according to Nylander. a Parmelia; and D. inanis, Mont. (Gaudich. in 
herb. Mont.!) clearly a Ramalina ; its relation to the generical type being 
not unlike that of Cetraria aculeata (the Dufourea of this group of Cetra- 
rie) to C. odontella and C. Islandica. And the very type of Acharius 
(D. mollusca, C. B. S., Herb. Sonder) is almost (or, according to Stizen- 
berger, quite) a Roccella. There remains only the little cluster of alpine 
lichens here referred to Dactylina, Nyl.; differing from Cetraria proper 
rather more than does C. aculeata ; and possibly also distinguishable by 
the spores. 
IV.—CETRARIA, Ach., Fr. 
Fr. L. E. p. 34. Scher. Spicil. (spp. excl.) p. 248. Tuckerm. Syn. N. Eng. 
p.13. Norm. Con. p. 12. Mass. Mem. (max. p.) p. 56. Stizenb. Beitr. 
loc. p. 175. Cetraria et Cornicularie spp., Ach. L. U. pp. 96, 124: 
Syn. pp. 226, 299. Eschw. Syst. pp. 20, 23. Koerb. Syst. pp. 7, H. 
Th. Fr. Lich. Arct. pp. 29, 35; Gen. pp. 49, 53. Cetraria et Cornic- 
ularia, Tul. Mém. pp. 22,170,175, t.10, f.5. Schwend. Untersuch. l.¢. 2, 
pp. 151, 177, t. 3, f. 30-33, t. 4, f.1-12. Cetraria, max. p., et Parme- 
lie f., Scheer. Enum. pp. 12, 48. Cetraria et Platysma max. p., Ny. 
Syn. 1, p. 298, t. 8, f. 32-5, 48. Cetraria, et Imbricarie sp., Anz. Catal. 
pp. 20, 29. Parmelie sect., Mev. Wallr. Eschw. Bras. 
Apothecia scutelleformia, subinde dilatata pelteformia, thalli 
marginibus apicibusve oblique affixa, disco thallo discolore. Spore 
subellipsoidec, simplices, incolores. Spermatia oblonga, apice altero 
1. sepius utroque incrassata vel cylindrica; sterigmatibus pauci- 
articulatis. Thallus adscendens, aut fruticulosus lobis 1. subteretibus 
1, canaliculato-foliaceis, aut expansus ; subcartilagineus. 
It cannot well be questioned, in view of Cetraria, that Usneei is imme- 
diately contiguous to Parmeliei, And universally accepted as is the sepa- 
ration of the bulk of the present genus from Parmelia, the limits of the 
two groups remain still uncertain. Scherer steadily insisted on even a 
conspecific relation between Cetraria tristis and Parmelia lanata, stygia, 
and Fallunensis; referring the cluster to the former genus in his earlier, 
and to the latter in his latest work; and he is by no means alone in recog- 
nizing the evident points of relationship between all these lichens. But 
the first of them (Cefraria tristis) is at any rate sufficiently alien in habit 
to Parmelia ; and we cannot wonder therefore that its systematic position 
should be still further perplexed. In referring this to his Cornicularia, 
Acharius took it for congenerical not only with Cetraria aculeata, Fr., the 
