156 LEPTOGIUM. 



5. L. rivale, Tuckerm.; thallus minute, tufted, microphyl- 

 line; greenish - lead - coloured j the narrow, ligulate, flexuous, 

 repand lobes crowded and imbricate ; apothecia (so far as seen) 

 immersed, and indicated by an ostiole. Spores cymbiform, 

 bilocular, decolorate, ^J mic. Obs. Lick. 4, 1. c. p. 170. 



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

 Mariposa," California, growing with and on Hydrotliyria, Buss. 

 (Bolander), Tuckerman in Schwend. Flecht. als Parasit. I. c. 

 1869.- Known as yet only in minute portions adhering to and 

 accompanying HydrotJiyria. The sunken fruit was first ob- 

 served, in the course of his examination of the thallus, by Prof. 

 Schwendener. 



6. L. albociliatum, Desmaz.; thallus middling-sized, rosu- 

 late, laciniate-lobate, greenish-lead-coloured becoming black- 

 ish-olivaceous ; the rounded divisions sinuately cut, crisped, and 

 crenate, and finally lacerate-denticulate, minutely ciliate with 

 white fibrils, now granulate or minutely lobulate at the centre ; 

 paler beneath where there is more or less of a fleecy nap ; apo- 

 thecia scattered, smallish, biatorine, sessile j the red-brown disk 

 soon convex, and the thin, paler margin disappearing. Spores 



cymbiform, bilocular, soon decolorate, ^J mic. Desmaz. in 



Ann. Sci. 4, 4, p. 132. Nyl. Scand. p. 35. Tuckerm. Gen. p. 95. 

 PolycUdium Cetrarioides, Anz. Catal. Sondr. p. 7. 



Among mosses on rocks, California (Bolander), Tuckerman 

 Gen. 1872. Silverton, Oregon, Hall. The European lichens 

 are probably all referable to the same reduced and ascendant 

 form (v. Cetrarioides) described by Anzi (Lich. Langob. n. 13) 

 and contrast sufficiently with the depressed and regular Cali- 

 fornian plant (formerly distinguished by me as L. leucothrix), 

 which differs also in the free extension of the white fibrils of the 

 upper side to the under ; but the latter is certainly no more 

 than the fully developed condition of the former. The medul- 

 lary layer is compact in this species. 



* * * Euleptogium. Thallus foliaceous. Spores ovoid-ellip- 

 soid, soon muriform. 



7. L. ccesiellum, Tuckerm. herb.; thallus crust-like, granu- 

 late -squamulose ; greenish-glaucescent, becoming sky-blue when 

 wet ; the very minute, scurfy squamules finally expanded, sub- 

 imbricate, and crenulate ; apothecia smallish, biatorine, adnate, 





