236 ALGiE CHLOROSPER3IE/E. [Scytonema. 



71. Stigonema. Ag. Stigonema. 



Filaments tufted, cylindrical, cartilaginous, branched, inarticu- 

 late, including granules ranged in transverse dotted rings. — 

 Name ; arto/iov, dotted, and vr//na, a thread. 



1. S. atro-virens, Ag. Black-green Stigonema. Tufted; 

 branches slightly divided, slender, attenuated, sub-acute ; rings 

 three, dotted. Conf. atro-virens, Dil/w. t. 25. — Lichen j>u- 

 hescens, E. Bot. t. 2318. Bangia atro-virens, Lyngb. — St. atrov. 

 Harv. in Hook. Br. Fl. v. ii. p. 368. 



Wet rocks in alpine situations, common. Forms broad, rigid, very 

 dark, loose tufts, 



2. S. mammillosum, Ag. Mammillated Stigonema. Branches 

 simple, incrassated, fusiform, densely mammillose. Ag. Syst. 

 p. 42. Harv. in Hook. Br. Fl. v. ii. p. 363. — Bangia mammil- 

 losa, Lyngb. t. 25. (very bad.) 



Bottoms of alpine rivulets. At the Eagle's Nest, Killarney. — This 

 forms extensive stratified tufts, and is of a softer and more flaccid sub- 

 stance than the preceding. Under the microscope it is at once recog- 

 nised by the very peculiar papillate branches. 



72. Scytonema. Ag. Scytonema. 



Filaments branched (very rarely simple), flaccid, tough, conti- 

 nuous, tubular. Endochrome brown or olivaceous, trans- 

 versely striate, " at length separating at the striae into lenti- 

 cular sporidia." Carm.— Name ; o-kotos, a skin, and vnfia, a 

 thread ; the filaments are tough. 



1. S. minutum, Ag. Dwarf Scytonema. Filaments minute, 

 erect, rigid, flexuose, fastigiate, collected in a dark crust ; 

 branches short. Harv. in Hook. Br. Fl. v. ii. p. 365. 



Rocks in alpine districts. At Carrigataha, near Caher, and at Kil- 

 larney. This forms dark irregular patches : the filaments are about a 

 line in height. 



2. S. myochrous, Ag. 3Iouse-skin Scytonema. Filaments 

 elongate, mostly decumbent, sub-rigid, flexuose, slender, yel- 

 low-brown ; branches issuing in pairs, at right angles with the 

 stem. Harv. in Hook. Br. Fl. v. ii. p. 365. — Conf. myochrous, 

 Dillw.t. 19. E. Bot. t. 1555. — ft. crinalis ; filaments tufted. 

 Conf. mirabilis, E. Bot. t. 2219. (according to the original spe- 

 cimens, but not C. mirabilis, Dil/w. t. 96. ) 



Alpine bogs and rivulets. (3. near Banhy, on Orthotrichum rivu- 

 lare ; Miss Hutchins. The geminate divaricating branches and dark 

 brown colour (when dry) well distinguish this species. 



3. S. contextum, Carm. Lnterwoven Scytonema. Filaments 

 mostly simple, interwoven into a tough olivaceous stratum, 



