OF ARTS AND SCIENCES. 171 



plumbeo, lobis imbricatis linearibus plauis repandis ; apotheciis (ostiolis 

 indicatis) iiniuersis. Sporje octonaj, e fusiformi ovoide^, biloculares, 

 incolores, loiigit. 0,01 6-23'""-, crassit. OjOOo-S"""-. Paraphyses parcse. — 

 " On small pebbles in the bottom of a clear brook around the Big Trees, 

 Mariposa," California (growing with and on Hydrothyria, Russ.) Dr. 

 Bolatider. Lobes scarcely exceeding 0,5 millim. in width. Texture 

 of the thallus parenchymatous throughout ; an outer row of polygonous 

 cells, distiusfuishable from the rounder and looser cells of the intei-ior, 

 indicating the cortex of the present genus. Collogonidia solitary, or 

 in very short chains. There is little in the lichen to remind one of 

 the equivocal Gollema rivulare, Ach., of Sweden, which yet agrees 

 with the other in the very interesting points of an entirely cellulose 

 texture and an aquatic habitat. The Californian plant was supposed 

 to be infertile ; but my friend Dr. Schweudener met accidentally with 

 an immersed apothecium in a section of the thallus which he was 

 examining, and I have since found such fruits to be indicated externally 

 by a distinct ostiolar margin. Whether there is ever any further de- 

 velopment or emergence of this apothecium is unknown. The small 

 material before me 2:ave no indication of lichenine with iodine. 



Placodium galactophyllum, sp. nov. : thallo crustaceo-adnato 

 areolato-squamuloso ambitu lobato, farinoso lacteo, detrito fulvo ; 

 apotheciis (latit. 0,5-0,9 millim.) zeorinis sessilibus plauis disco auran- 

 tiaco tenuiter marginato. Sporte octonte, polari-biloculares, incolores, 

 longit. 0,008-1 4"""-, crassit. 0,00-4-6"'"'-. Tuckerm. Gen. Lich. p. 108. 

 — On lime rocks, Chase Co., Kansas, E. Hall, 1871. A distinctly lobed 

 lichen with the habit of Lecanora muralis v. albo-pulverulenta, Schier. 

 {Lich. Helv. n. 334) and differing in this respect from even the best 

 condition of the European P. erythrocarpium ; the spores of which are 

 also larger, and not rarely measure, in my specimens Vn^- ^^^- Apo- 

 thecium of our lichen distinctly lecanorine, with marginate disk. 



Placodiuji FERRUGIN0SU5I, sp. nov. : thallo crustaceo rimoso-areo- 

 lato aurantiaco, areolis subinde lobulatis, hypothallo nigro ; apotheciis 

 (latit. 0,6-0,9 millim.) biatorinis sessilibus ferrugineis (nigricantibusque) 

 maro-ine demum flexuoso. SporiE octonas, polari-biloculares, incolores, 

 lono-it. 0,016-2r"'"-, crassit. 0,006-9"""-. — Volcanic rocks, Island of Chi- 

 loe, Chili, Dr. T. Hill (Hassler exp. 1872). Almost P. cinnaharinum, 

 as respects the thallus, but with the apothecia almost of P.ferrugineum. 



Placodium ferruginecm (Huds.) Hepp, * miniaceum ; apotheciis 

 miniatis. — On buslies, Cape of Good Hope, C. Wright. The appressed 

 apothecia differing only, but remarkably, iu color, from Cape specimens 

 of P. ferruginemn (Drege in herb. Sonder ; Wright), which are uudis- 

 tiniruishable from the northern lichen. 



