OF ARTS AND SCIENCES. 175 



RixoDiNA MiLLiARiA, sp. iiov. : tluxllo ci'ustaceo teniii verruculoso 

 viridi-fuscescente ; apotlieciis perminutis (latit. circa 0,2-0,'l: mm.) ad- 

 natis lecanorinis, disco fusco-nigro opaco plano-convexo, margiue tenui 

 integro dein uigricante vel excluso. Hypotlit'cium fusco-nigrum. 

 Spor?e octona?, obtuse ellipsoidea^, biloculares, fiisav, longit. 0,009-1 5"""-, 

 crassit. 0,005-8"""', parapliy!>ibus demum distioctis, fiisco-caiaitulatis. 



A common bark-lichen about Boston, and found also at New Bed- 

 ford, H. WiUey ; and in Western New York, Miss Wilson. It is 

 differenced from ordinary R. sophodes v. exigna by its blackened hypo- 

 tbeciura, — a character, in this place, of some interest. The spores 

 occur now in twelves according to Mr. Willey, a variation like the 

 well-known one in the v. exigua (constituting R. jiolyspora, Th. 

 Fr.). But our lichen is also curious as seeming to exiiibit filiform, 

 bowed spermatia (0,012-20"™- long) on simple sterigmas. This obser- 

 vation has been made repeatedly both by Mr. Willey and myself, and 

 we are unable to refer the black, papillteform spermogones and contents 

 in question to any other lichen than the one upon whose thallus they 

 occur, though it appears quite inadmissible, in present knowledge, that 

 they can belong to it. 



Pertusaria thamnoplaca, sp. nov. : thallo fruticuloso cartilagineo 

 appresso dichotomo-ramoso albido-fuscescente, ramis subteretibus papil- 

 lato-verrucosis subtus albis fibrillis sparsis concoloribus ; apotheciis de- 

 presso-globosis monothalamis mox papillato-coronatis (latit. dein 1 mm.) 

 ostiolo punctiformi nigro. Sporte octonte, ellipsoidece, simijlices, inco- 

 lores, longit. 0,0o0-72'"'"-, crassit. 0,023-38™™-. 



Trunks, ShoU Bay, near the western entrance of the Straits of Ma- 

 gellan, orrowing with and often on the next, Rev. T. Hill (Ilassler exp. 

 1872). Another illustration of the fruticulose thallus in a properly crus- 

 taceous group ; and more remarkable than either of those described from 

 our own Pacific coast (Lich. Calif, in loc). Thallus (reaching a diameter 

 of more than two inches) closely appressed and affixed by its fibrils to 

 the matrix, dichotomously much branched, either terete or now a little 

 compressed, and in the larger parts almost attaining a thickness of one 

 millimetre. The whole is besprinkled, at length densely, with crowded 

 papillie, which surround the apothecia with one or more coronals, and 

 hide often, to a considerable degree, the branches. Under the micro- 

 scope, the direction of the very minute and confused network of fila- 

 ments which makes up the interior of the thallus is seen to be on the 

 whole longitudinal. 



Pertusaria colobina : thallo crustaceo uniformi papillifero, papil- 

 lis dein confertis, centralibusque subelevatis ; apotheciis ab iis P. tham- 



