THELOTREMA. 225 



5. T. Domingense (Fee; Nyl.) Tuckerm. ; thallus cartila- 

 gineous, smoothish, becoming wrinkled and granulate; glau- 

 cescent, passing now into brownish-cream-coloured; or now 

 white ; apothecia small to almost middling-sized, adnate, glob- 

 ular, at length depressed ; more or less thickened ; urceolate ; 

 aperture poriform, obtusely margined by the exterior exciple, 

 through which the toothed border of the black proper exciple 

 finally protrudes; disk colourless, without interior exciple. 

 Spores solitary, or in twos; fusiform; 20-40-locular ; ^^-mic., 



fuscescent or colourless. Tuckerm. Gen. p. 137. Ascidium 



(Fee] Nyl. Enum. Gen. ; & in Prodr. N. Gran. p. 50. 



b. rhodostroma, Nyl. ; the white interior of the exciple be- 

 coming rose-coloured. Nyl. 1. c. Ascidium, Mont. Guy. n. 



46, t. 16, f. 4. 



On various trees, Mississippi (Dr. Veitch), Tuckerman I. c. 

 1872. South Carolina, fiavenel Florida, Austin. b, Louis- 

 iana, Hale. Georgia, Eavenel. Ascidium, as understood by 



Montague, the chief illustrator of this type, offers nothing to 

 distinguish it generically from his Thelotrema depressum but 

 the at length doubtless marked thickening of the thalline por- 

 tion of the exterior exciple; and it is perhaps easier to refer 

 the type to the present genus, than, with Nylander, to under- 

 take to make the cited Thelotrema into an Ascidium. 



* * Spores muriform-plurilocular, brown. 



6. T. interpositum (Nyl.) Tuckerm. herb. ; thallus thin, un- 

 even ; glaucescent and pale-cream-coloured ; apothecia of the 

 size of the last, superficial, globular ; scarcely thickened ; urce- 

 olate ; the poriform aperture bordered obtusely (much as in the 

 last preceding) by the exterior exciple ; the black disk covered 

 thickly by a white veil, contrasting in section with the thick, 

 black proper exciple. Spores solitary or in twos ; fusiform ; the 

 transverse series of spore-cells about forty, of about six mem- 

 bers each, in the middle ; ^"^ mic. Ascidium, Nyl. in Prodr. 



N. Gran. p. 50, note. 



On bark, Texas, Hall. An Ascidium, like the last species ; 

 from which it more especially differs in the spores. Thelotrema 

 postpositum, Nyl. (in litt. 1864 ; before referred by him to his 

 T. monosporum, Prodr. N. Gran. p. 46), a Louisiana lichen 

 (Hale), has a little smaller fruit, in the scanty specimen received, 

 but is otherwise undistinguishable. 

 15 



