CRYPTOGAMIA ALG^. 249 



vula, Crypt. Fl t. 360.) in a mature state." To Dr GRE- 

 VILLE'S opinion much weight is due, but the differences 

 pointed out between our plant and Z. deusta appear to me 

 too slight to warrant their separation ; nor can I think Z. 

 parvula distinct. 



156. ULVA. 



* Frond tubular. 



1. U. intestinalisj frond simple, round, elongate, membranaceous, 

 green, inflated LIGHTF. Scot. 968. WITH, iv. 141. HOOK. 

 Scot. ii. 91- Fistularia intestinalis, GREV. Fl. Edin. 300. Enter o- 

 morpha intestinalis, GREV. Alg. Brit. 179. 



Hal. In the Tweed within tide-influence, plentiful in 

 summer. 



Varies very much in regard of size. Specimens are not un- 

 common nearly one yard long, which, when perfect and 

 filled with water, resemble the intestines of an animal, 

 whence the specific name ; but in general it is much less 

 than this. It often swims upon the surface of the water 

 in clusters like a scum, and looks bloated as if in a state of 

 fermentation. 



2. U. compressa, frond green, branched, compressed, tubular ; 

 branches irregular, simple, attenuated at their base. LIGHTF. 

 Scot. 969. HOOK. Scot. ii. 91. Fistularia compressa, GREV. FL 

 Edin. 300. Enteromorpha compressa, GREV. Alg. Brit. 180. 



Hab. Sea shores and in the Tweed, abundant. 



This and the preceding, during the summer months, fill the 

 bed of the lower part of the river, and by clogging his 

 nets, become a serious obstruction to the fisherman, who 

 knows them by the name of Slake. 



* * Frond plane. 



3. U. laciniata, frond purple, umbilicate, sessile, spreading, torn 

 into irregular segments and waved. LIGHTF. Scot. 974. t. 33. 

 Porphyra laciniata, GREV. Alg. Brit. 16H. 



Hab. On rocks, abundant. 



This is the true Laver, a vegetable in common use at the 



L 3 



