ACOTYLEDONS. ALG^. FllCUS. 93 



tally in pairs ovate obliquely but shortly beaked upon a short 



straight peduncle. Ag. p. 49. Conferva vesicata, Dillw. 



Conf. t. 49. Cow/, amphibia, Lightf. p. 9/9. Dillw. t.4\. 

 HAB. Ditches, Lightf. 

 Several aquatic species of this genus were included, by Linnaeus and 



the older botanists, under the name of C. amphibia. 



** Growing on the earth. 



3. V. Dillwynii, filaments flexuose, vesicles sessile lateral glo- 

 bose. Ag.p.bQ. Conferva frigida, Dillus. t. 16. 



HAB. Upon the ground in damp situations. 



It seems very doubtful if the number and form even of the vesicles is 

 to be depended upon as constituting specific distinctions. This is 

 probably but a var. growing upon land of V. caspitosa. Filaments 

 1 or 2 inches long, branched,, intricate, forming a green stratum on 

 the earth. 



4. V. ? radicata 9 (( filaments rooting, vesicles solitary terminal 

 globose." Ag. p. 52. Viva granulata, Lightf. p. 976. Tre- 

 mella granutata, E. B, t. 324. 



HAB. On the perpendicular banks of rivers and lochs, in shady places, 

 not unfrequent, Lightf. 



This seems of doubtful genus, and I confess myself never to have seen 

 the filaments, described by Agardh, the existence of which has in- 

 duced that author to place the plant among the Vaucher'we. Agardh 

 says the filaments are clustered, very short, rooting below the soil, 

 and branched, green above, colourless at the base. The vesicles are 

 green, nearly as large as hemp-seed, and not elevated at all above 

 the soil, full of a watery fluid within. The membranous coat has 

 internally a number of small granules imbedded in it, which Agardh 

 does not appear to have seen. In dry weather the upper part of 

 the vesicles collapses, sinks in, and the vesicle becomes cup-shaped. 



Div. IV. FUCOIDE^;. Fruit : either naked seeds immersed in 

 the frond, or capsules included in proper receptacles. Frond 

 continuous. Texture fibrous, Jibres longitudinal, intricate. 

 Substance coriaceous or cartilaginous. Colour olive-brown, 

 lecoming black by exposure to the air. 



21. FUCUS. 



Receptacles tuberculated, tubercles perforated, containing within 

 clustered capsules, mixed with jointed fibres. 



\. F. natans, stem compressed filiform pinnated, branches al- 

 ternate simple, leaves linear-lanceolate serrated, vesicles sphae- 

 rical on flat petioli, receptacles cylindrical racemose. Turn, 

 fiist. Fuc. .46. E. B. J. 2114. 



HAB. Cast on shore occasionally among the Orkney islands, but 

 wafted probably from the W. Indies, Mr. P. Neill. 



In some more southern seas this species floats in such immense quan- 

 tities as to impede the progress of ships. 



