242 SCYTONEME^I. 



sulphureous properties, as if the hepatic gas were necessary 

 to its production and nourishment." Dillw. 



5. TOLYPOTHRIX KUFESCENS. 



Plate LXIX. Fig. 7. 



Char. Filaments minute, spreading in a thin slimy purplish 

 stratum. 



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

 Harv. in Manual, p. 158. 



Hob. 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 power of the com- 

 pound microscope." Carm. MS. 



b. Branches adherent to the main filaments. 



6. TOLYPOTHRIX DILLWYNII Hass. 

 Plate LXVIII. Figs. 4, 5. 



Char. Filaments tufted. Branches subulate, adherent to the 

 principal threads nearly their whole length. Striae about 

 a diameter from each other. 



Scytonema Dillwynii Harv. et Ralfs' MS. 

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

 Mr. Moore. 



This species was named by Harvey Scytonema Dillwynii, 

 under the impression that it was the Microcoleus ? Dillwynii 

 of his " Manual," and the Conf. vaginata of Dillwyn, 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 



