OF ARTS AND SCIENCES. 407 



as if powdery, at length finely rugulose, or rimulose-verruculose surface, 

 which is beset, more or less thickly, with isidioid, elongated, rarely at 

 length branched excrescences, attaining to more than a line in length ; 

 from pale greenish-gray becoming ashy-gi'ay. Apothecia large (the 

 larger ones little less than a line in diameter), innate, urceolate- 

 scutelliform, at length much dilated ; the exterior exciple bordering, 

 with an incurved lacerate margin, the black disk, which is covered 

 with a white bloom (becoming thicker, and more crustaceous, when it 

 is broken and perforated, as in T. schizocarptim, herein described, and 

 other species), and is seen, in a section, to be enclosed by a pale-brown- 

 ish line, extending above it into the thalline margin. Interior exciple 

 indistinct. Spores of middling size, dark-brown, from subcocciform 

 becoming ovoid-ellipsoid, and at length rather oblong, or attenuate at 

 one end (dacryoid, Koerb.), the length from once and a half to four 

 times exceeding the diameter. Certainly akin to a much smaller 

 southern lichen, which is referred by Dr. Nylander to a variety of his 

 T. compunctum. The latter was regarded a species of Urceolaria by 

 Acharius, and the present has much of the same aspect ; but it is, I 

 think, inseparable from Thelotrema. Paraphyses indistinct, but ap- 

 parently filiform. 



Thelotrema leiostomum, sp. nov. : thallo tenui effuso lasvigato 

 rimuloso-verruculoso glaucescente ; apotheciis immersis rotundatis 

 aut confluenti-difformibus (lirelliformibus), excipulo exteriori urceolato 

 margine prominulo integerrimo albido discum nigricantem velo sub- 

 crustaceo margini concolore demum perforate vestitum cingente. 

 Sporte octon^, fuscee, ellipsoideae, demum oblongo-ellipsoideae, septis 

 3 sporoblastisque regularibus 4, diam. 2-3-plo longiores. Trunks, 

 island of Cuba, 3Ir. Wright. Thallus smooth, glaucescent. Apothecia 

 immersed, minute, rounded, but confluent at length, and passing into 

 irregular, often lirelliform shapes, often approaching a line in length ; 

 the exterior exciple bordering the sunken, blackening disk, with a 

 slightly prominent, smooth and entire, white, or pale cream-colored 

 margin; the thickish, smoothish veil, which covers the disk, and 

 becomes at length, in the larger apothecia, perforated, in the manner 

 of T. Auberianum, being of the same color with the margin. Spores 

 regularly elHpsoid, brown, with three dissepiments and four regular 

 sporoblasts ; the length from twice to thrice exceeding the diameter. 

 Paraphyses filiform, distinct. 



Thelotrema Cubanum, sp. nov. : thallo effuso tenui Isevigato ru- 



