Thelotrema.] I.ICHENES. 161 



lated olive-brown smooth black-edged, warts of the apothecia 

 very large and irregular with numerous cells and numerous 

 black slightly depressed often confluent and then linear curved 

 points. — Opegrapha crassa, DC. — Stigmatidium crassum, Dabis 

 in Sot. Gall. v. 2. p. 643. — S. obseurum, Spr. (excl. Syn. Pers.) 

 — Enterographa crassa, Fee. — Lichen obscurus, E. Sot. t. 1752. 

 (excluding the Syn.) — Porina aggregata, and P. saxicola, Ach. 

 according to Sprengel. 



On the bark of old trees. — This, Sir James E. Smith referred to Ar- 

 thonia of Acharius, and supposed it was the A. obscura of that author : 

 while others, Fee and Meyer, have made of it a distinct Genus, the former 

 under the name of Enterographa, the latter of Stigmatidium, still arrang- 

 ing it with the Grajohidece. But the real nature of the fructification is 

 well represented in E. Bot., and Mr. Borrer justly observes that it is 

 only when the tubercles (or, in allusion to the structure of Pcrtusaria, 

 the depressed points of the warts) become confluent, that the plant 

 assumes the appearance of an Arthonia. 



8. Thelotrema. Ach. Thelotrema. 



Thallus crustaceo-cartilaginous, spreading, adnate, uniform. 

 Apothecium double, the outer consisting of an open wart formed 

 of the thallus, the inner (one or two) thin, membranaceous, 

 breaking away at the top, its disk containing a nucleus. — Named 

 from ^tjXtj, a wart, and r^/j/xa, a perforation ; an open or per- 

 forated wart. — This Acharian Genus is retained by Mr. Borrer, 

 and if it were confined to our first and second species, it 

 would appear to have a structure very unlike that of the other 

 Lichens, and they may be considered the type of the Genus. 

 But the other species differ considerably in habit, and assuredly 

 in their fructification also. 



1. T. lepadi/iuui, Ach. (ividc-moutlted Thelotrema); crust 

 smooth cream-coloured, warts of the apothecia smooth conoid 

 truncated, inner apothecia ( 1 — 2) hollow pale-brown with a 

 thin inflexed edge. Ach. &yn. j>. 1 L5. Schar, Licit, //dr. 

 j>. (>7. >/. 121. — Lichen inchuns, E. Sot. t. 678. 



On the bark of trees, not unt'requcnt. 



2. T. mclahiiriini. Turn, and Burr. {suKill-nwiitlml T/uIn- 

 In ma ); crUgtaceOUJ cream-coloured, warts of the apothecia 



eo-ivex opening by an irregular inflexed orifice, inner apothecia 

 depressed brown with a thin obsolete jagged border. Turn. 



an, I llorr. in /:'. B<H. t. 2461. 



On the smooth bark Dfyoung Oaks, Sussex, /l/V. Horrcr; on that of 



r h, Argyleshfre, ('apt. Carmichtoel. — '1 his appears to me to be onty 



a VOOnB state of the preceding, and, if I am not mistaken, dipt. Car- 



miihael entertained the same opinion. 



3. T. : i ninth, ■mtitii inn, Ach. (trajitin '/'//< h>tn inn ); crust 



Bubtartar i^ thin continuous ash-eolSured, vfartti of ihe apo- 

 thecia hemisphtericfe] Witfc a radiated Orifice (their cavity Mink 



into the stone ), inner apothecia concave DOSh-l olonred depressed 



M 



