126 THELOCARPON INTERMEDIELLUM. 



absorption of the solution, which indeed can hardly be called a 

 reaction, being merely an instance of mechanical mixture. 



This rare and interesting lichen, which has been hitherto found 

 in Finland only, occurred near Shrewsbury, Dec, 1873, on the sur- 

 face of old leather — the sole of a shoe — lying exposed in a fallow 

 field. On showing it to my friend, the Rev. W. A. Leighton, he 

 at once recognised it as T. intermediellum of Nylander, and afforded 

 me every facility for comparing it with other species in his valuable 

 herbarium. The fact will be known to British Lichenists that we 

 owe to Mr. Leighton the discovery in this country of the only two 

 species as yet recorded in our Flora, namely — T. Laureri (Flot.), 

 and T. epithallinum, Leight., out of the nine species at present 

 known in the genus. I am much gratified to be able to add T. 

 intermediellum, Nyl., to the list of British species. 



Explanation of Plate XXI. 



a. TTielocarpon intermediellum, Nyl. Nat. size. 



b. Apothecium side view, much enlarged. 



c. Upper surface of the same. 



d. Section of the same with asci in situ, sporidia escaping by the pore. 



e. Asci filled with sporidia, others immature. 



f.g. Filaments growing from the sides of the interior of the perithecium. 

 h. Sporidia much enlarged. 



FRUITING OF MASTIGONEMA. 



Dr. Wood has described, in his new and interesting work on the 

 Fresh Water Algae of the United States, a new species of Masti- 

 gonema, which he calls M. fertile. His remarks upon this species 

 are of interest to Algologists. He says — " I found this plant in a 

 stagnant pool in ' Bear Meadows,' forming a filamentous, felty 

 mass, with GEdogonium echinatum and other algae. The variously 

 curved and interlaced flexible filaments are always simple, and of 

 uniform, or nearly uniform, diameter through their whole length ; 

 excepting that, in some instances, there are small, local, bulbous 

 enlargements of the sheath. Though the ends of the filaments, in 

 all the specimens I have seen, are abruptly truncate, it is very pos- 

 sible that in the young trichoma the apex is prolonged into a long 

 hair, as in most of the Mastigonema. The inner filament is some- 

 times very distinctly articulated, often, however, it is not at all so. 

 The sheaths are firm, not at all lamellati, and generally project 

 beyond the inner trichoma. The spores are cylindrical, yellowish, 

 with a pretty distinct, although very close coat. They are always 

 enclosed in distinct cells, and are mostly several in a filament, 

 placed at intervals in its length." 



This is the first instance, at least that I know of, in which a 

 species of this genus has been found in fruit, and it is interesting 

 to note the resemblance of the spores to those of the more commonly 



