VAUCHEKIA.

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

This species would appear to be one of the rarest of thegenus. I have myself never encountered it.

8. Vaucheria sessilis Vauch.

Plate IV. Fig. 2.

Char. Capsules pyriform, large, sessile.

Ectosperma sessilis Vauch. Hist, des Conf. d’Eau douce ,Grev. Algae Brit. p. 192. ; Hook. Br. FI. p. 320.; Eng.Bot. t. 1765.; Harv. Manual, p. 148.

This is one of the most abundant species of the genus.The vesicles are almost as often solitary as in pairs ; and inthis state I apprehend it constitutes the Vaucheria dichotomaof writers. The spores are frequently noticed to be of areddish colour. This appearance is common to all the speciesof the genus, and is probably the result of age, and also anindication 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 toboth. Anther intermediate.

Ectosperma geminata Vauch. Hist, des Conf. p. 29. pi. ii.fig. 5.; Grev. Alga; Brit. p. 193. t. 19 .; Hook. Br. FI.p. 320.; Eng. Bot. t. 1766.; Harv. Manual, p. 148.

The filaments of this species are much finer than those ofany of the preceding ; the seed-vessels, too, are smaller, andrepresent a sphere hollowed out on the inner side, or towardsthe anther. The peduncle is common to both seed-vessels:after ascending for some distance from the filament fromwhich it rises, it sends off laterally two branches, on each of

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