VAUCHERIA. 55 



Hab. Near Bristol : JV. W. Young. About Edinburgh : Dr. 

 Grcville. 



This species would appear to be one of the rarest of the 

 genus. I have myself never encountered it. 



8. Vaucheria sessilis Vauch. 

 Plate IV. Fig. 2. 

 Char. Capsules jjyriform, large, sessile. 

 Ectosperma sessilis Vauch. Hist, des Conf. d'Eau douce, 

 Grev. Alga) Brit. p. 192. ; Hook. Br. Fl. p. 320. ; Eng. 

 Bot. t. 1765. ; Harv. Manual, p. 148. 



This is oue of tlie most abundant species of the genus. 

 Tlie vesicles are almost as often solitary as in pairs ; and in 

 this state I apprehend it constitutes the Vaucheria dichotoma 

 of writers. The spores are frequently noticed to be of a 

 reddish colour. This appearance is common to all the species 

 of the genus, and is probably the result of age, and also an 

 indication of the presence of azote. 



c. Vesicles pedunculate, in pairs, lateral. 

 9. Vaucheria geminata Vauch. 

 Plate III. Fig. 1. 



Char. Capsules situated on a divided peduncle, common to 

 hath. Anther intermediate. 

 Ectosperma geminata Vauch. Hist, des Conf. p. 29. pi. ii. 

 fig. 5. ; Grev. Alga3Brit. p. 193. t. 19 . ; Hook. Br. Fl. 

 p. 320. ; Eng. Bot. t. 1766. ; Harv. INIanual, p. 148. 



The filaments of this species arc much finer than tliose of 

 any of the preceding ; the seed-vessels, too, are smaller, and 

 represent a sphere liollowed out on the inner side, or towards 

 the anther. The peduncle is common to both seed-vessels : 

 after ascending for some distance from the filament from 

 which it rises, it sends off laterally two branches, on each of 



E 4 



