292 



Hydroph. p. 200. t. 68 a. ; Harv. in Hook. Br. Fl. p. 399. ; 

 also in Manual, p. 184. ; Meneghini, loc. cit. p. 114. 



Hob. In freshwater pools near the coast ; rivulet near 

 Torquay : Sir W. J. Hooker. Appin : Captain Car- 

 michael. 



" Fronds unattached, scattered at random in the clefts of 

 the rocks, globular, smooth, olive-green, diaphanous, from \ to 

 1^ inches in diameter, the larger ones generally compressed, 

 hollowed, and sometimes ruptured." Carmichael. 



The filaments, as remarked in the description of the pre- 

 ceding species, resemble those of Nostoc verrucosum in all, save 

 size, being larger than in that species. The reproductive cells 

 are rarely produced. 



8. NOSTOC MUSCORUM Ag. 

 Plate LXXIV. Fig. 4. 



Char. Frond tuberculate, subcoriaceous, variable in shape. 

 Filaments much curved, moniliform, exceedingly slender. 



Ag. Disp. p. 44. ; Ag. Syn. p. 132.; Syst. p. 19. ; Harv. 

 in Hook. Br. Fl. p. 399. N. mnscorum Harv., in 

 Manual, p. 183. N. microscopicum Carm., MS.; Harv. 

 in Manual, p. 184. ; Meneghini, Nostochinearum Italica- 

 rum, p. 1 1 9. 



Hob. N. muscorum, on calcareous rocks, and the mosses 

 which cover them, Appin : Captain Carmichael. N. 

 microscopicum, on exposed calcareous rocks among 

 mosses, Appin: Captain Carmichael. Near Youghal: 

 Miss Ball. Wilderness, near Clonmel : W. H. Harvey. 

 Clayey banks, co. Antrim : Mr. Moore. 



I have examined several of Carmichael's specimens of this 

 Nostoc, and compared them with others of Nostoc micro- 

 scopicum Carm., and I entertain no doubt of the specific 

 identity of both. All the specimens which I have received 

 of the former have consisted not of single fronds, but of an 

 aggregation of numerous smaller fronds of various sizes and 



