UlvaceceJ] ulva. 329 



most distinguished botanists are of opinion that they are 

 varieties of one species. " Few plants/^ says Professor 

 Harvey, in his Manual, " are so sportive in size and rami- 

 fication, and if all the varieties were described, the species 

 might easily be multiplied till we should have one for 

 almost every marine pool ! " 



Genus XCVI. ULYA, Linnams. 



Gen. Char. Frond membranaceous, of a green colour (in 

 some cases saccate, and inflated in the young state) . Fructifica- 

 tion, minute granules mostly arranged in fours. — Grepllle. The 

 name is from the Celtic word, ul, loaier. 



1. Ulva latissima, Linn, (Plate XIX. fig. 73.) 

 Hab. On rocks and stones in the sea. Annual. To be 

 found, however, more or less during all the winter. 



Fronds from four to eighteen inches long, and of con- 

 siderable breadth, of an oblong shape, and waved at the 

 edges. It is tender in substance, of a deep green colour. 

 It adheres well to paper in drying in the early part of the 

 season, the shading produced by the waved margin adding 

 to the beauty of the specimens. It is called oyster-green^ 

 because employed to cover oysters. It is also called green 



