396 PROCEEDINGS OF THE AMERICAN ACADEMY 



ing six inches in length) ; the thin, smooth epidermis becoming here 

 and there uneven, but not squamulose ; straw-colored, becoming pale- 

 yellow towards the summits ; dividing sparingly and irregularly into 

 elongated, spreading, more or less intertangled branches, which are 

 mostly scyphiferous, but occur occasionally with subulate tips. Sterile 

 scyphi very small, proliferous from the margin (or very rarely from 

 the centre), toothed ; the teeth often crowned with the spermagones. 

 Fertile podetia somewhat dilated, especially above, when the epidermis 

 becomes less regular, and the axils are sometimes (atypically) perfo- 

 rate ; the scyphi, by prolification from the margin, becoming in this 

 condition much divided or fimbriate-radiate. Apothecia scarlet. As 

 G. leporina, Fr., represents C. rangiferina, in the scarlet series, the 

 present may be taken as analogous, in that series, to C. gracilis in the 

 Fuscescentes, F'r., and C. amaurocrcEa in the Ochroleuc(B. It is slen- 

 derer than the lar^t-named, but sometimes not wholly unlike it. Of the 

 scarlet-fruited group, C. hellidifiora is possibly nearest, and passes into 

 states distantly approaching some specimens of the present, but the 

 former is confined to arctic and alpine districts ; and the extreme 

 slenderness and smoothness of the delicately-corticate, long-branched 

 podetia of C. gracilenta, and their different habit, is quite enougli to 

 separate this inhabitant of tropical savannas. 



DACTYLINA, Nyl. Syn. p. 28G. — The genus Dnfourea was pro- 

 posed by Acharius (Lichenogr. pp. 104, 524, t. 11, f. 2) for a Cape of 

 Good Hope lichen {Parm. mollusca, Ach.) akin to Roccella, which has 

 since been separated by De Notaris as Comhea. Only this was illus- 

 trated by the author, as expressing the type of the new genus ; and 

 though he associated with it a plant not congenerical {P.jiammea (L.), 

 Ach., also from the Cape, the spores of which relate it to Physcia pa- 

 rietina), and even gave precedence to this last in the Synopsis, the cita- 

 tion here, immediately after the name of the genus, of his figures (of 

 D. mollusca) in the Lichenographia, apparently showed that his type 

 remained the same. It is not, therefore, without reason that Mr. Th. 

 Fries (Genera Heterolich. Eur. p. 113) proposes to retain Dufourea 

 for D. mollusca. But Acharius added to the above-named, as " species 

 dubiae," several licliens of moi'e or less similar habit, the fructification 

 of which he was unacquainted with, and one of these {D. madrepori- 

 formis), though still only known in a sterile condition, which can ill 

 determine a generic type, has represented Dufourea with many lichen- 

 ists. To this, the remarkable lichen of Arctic America upon which 



