242 SCYTONEMEiE. 



sulphureous properties, as if the hepatic gas were necessary 

 to its production and nourishment." — Dillw. 



5. TOLYPOTHRIX RUFESCENS. 



Plate LXIX. Fig. 7. 



Cha?'. Filaments minute, spreading in a thin slimy purplish 

 stratum. 

 Calothrix rufescens Carm.; Harv. in Hook. B. Flor. p. 368.; 



Harv. in Manual, p. 158. 

 Hab. On rocks under the spray of cascades, Appin: Cap- 

 tain Carmichael. 



" Crust or stratum of indefinite extent, and so thin as to 

 seem a mere discoloration of the rocks until the finger is 

 passed over it, when a certain sliminess detects the presence 

 of the plant. Filaments half a line in length, and so slender 

 as to appear mere lines under the highest jjower of the com- 

 pound microscope." — Carm. 3IS. 



b. Branches adherent to the main filaments. 

 6. ToLYPOTHRIX DlLLW^YNII Hass. 



Plate LXVIII. Figs. 4, 5. 



Char. Filaments tufted. Branches subulate, adherent to the 

 principal threads nearly their ichole length. Striae about 

 a diameter from each other. 



Scytonema Dillioynii Harv. et Ralfs' MS. 



Hab. Dolgelly : Mr. Ralfs. Moist rocks, co. Antrim : 

 Mr. Bloore. 



This species was named by Harvey Scytonema Dillwynii, 

 under the impression that it was the Microcoleus ? Dillwynii 

 of his "INIauual," and the Conf vaginata of Dillwyu, t. 99. 

 which it is difficult to conceive from Dillwyn's description 

 that it really is. I felt much inclined to place this plant by 



