226 THELOTREMA. 



7. T. lepadinum, Acli. ; thallus commonly thin-membrana- 

 ceous and smoothish, but becoming thicker, wrinkled and dull ; 

 whitish, and cream-coloured; apothecia superficial, small to 

 almost middling, truncate -conoidal ; or also depressed and at 

 length urceolate-scutellaeform j interior exciple lax, persistent ; 

 as is normally the exterior one ; disk blackening above, white- 

 pruinose. Spores solitary ; or in twos, threes, and fours ; fusi- 

 form: the transverse series of spore-cells about thirteen to 



oc K/t\ 



twenty, of two to five members, the smaller-sized spores -V ; 



P>4 -.n/i O-O 



the larger and fewer -jg~ mic. L. U. p. 312. Fr. L. E.p. 



428. Koerb. Syst. p. 330. 



Trees, Arctic America (Richardson), Hooker I. c. 1823. New 

 England, rare, Tuckerman; Willey. Low country of South 

 Carolina, Eavenel. Louisiana, Hale. California, Bolander. 



Oregon, Scouler; Hall. Exterior exciple often pale -brownish, 



indicating the presence of a thin, brown proper exciple, con- 

 stituting the inner side of the other, but now apparently obso- 

 lete ; as is also rarely the whole exterior exciple (Louisiana, 

 Hale}. Interior exciple, in a depressed form of the fruit, now 

 doubled (f. diploloma, South Carolina, Eavenel). 



8. T. leprocarpum (Nyl.) Tuckerm. ; thallus very thin, un- 

 even; glaucescent; apothecia middling-sized, innate, dilated; 

 rounded and difiform ; the exterior margin irregularly reflexed 

 and cleft ; and, as well as the flat, colourless disk, white-pow- 

 dery ; interior exciple deficient. Spores solitary, or in twos, or 

 fours ; oblong ; the transverse series of spore-cells ten to four- 

 teen, of four to five members in the middle, ^ mic. Gen. 



Lich p. 139. Gr aphis, Nyl. in Prodr. N. Gran. p. 85. 



On Bald Cypress, Louisiana (Hale), Tuckerman Gen. 1872. 



The high authority of Nylander in Graphidacei gives a 



peculiar weight to his reference of this lichen, but appears still 

 insufficient to obscure its affinity to the Thelotrema leucastrum 

 of the present writer's Obs. Lich. 3, I c. p. 269, or of the latter 

 to the T. platycarpum and T. platycarpoides of the same 

 memoir. 



9. T. Auberianum, Mont. ; thallus membranaceous-cartila- 

 gineous, chinky, rugulose, or granulate ; greenish-glaucescent, 

 and brownish-cream-coloured ; apothecia innate becoming su- 

 perficial, small to middling-sized, rounded and variously dif- 

 form and confluent ; the elevated exterior exciple from rounded 



