THE MARINE ALG^ OF NEW ENGLAND. 43 



3. Yar. Lactuca, Le Jolis. (U. latissima, Harv., partim. —Phycoseris 

 gigantea, Kiitz.) 



Frond orbicular, oblong or elongate-fasciate, simple, undivided or 

 scarcely lobed, frequently spirally contorted. 



y. Tar. latisstiyta, Le Jolis. 



Frond simple, at first cuneate-substipitate, afterwards broadly ex- 

 panded. 



Very common all over the world, especially in brackish waters. 



The present species nearly corresponds to the Ulva latissima of the Nereis Am. Bor., 

 lint is not the U. Lactuca of that work. It is distinguished from the remaining species 

 by being always flat, never tubular at any age, and by its more or less orbicular out- 

 line not becoming linear or ribbon-shaped. Var. a is the common Ulva on rocks and 

 in pools exposed to the action of the waves. The frond, although not very large, is 

 rigid, and does not adhere well to paper in drying. In outline it is orbicular, and is 

 generally deeply incised. Var. 6 has a more elongated shape, and is generally plicato- 

 undulate. Var. y is very common in brackish places on the mud, and attains a very 

 large size. When fully grown it has no definite shape, but is ragged on the margin 

 and often perforated. 



Ulva enteromorpba., Le Jolis. 



Frond linear or lanceolate in outline, attenuated at base, the two lay- 

 ers of cells either entirely separating, so as to form a tubular frond, or 

 slightly cohering, forming a flat frond. 



a. Yar. lanceolata, Le Jolis. ( Ulva Linza, Greville & Harvey. — 

 Phycoseris lanceolata and crispoM, Kiitzing.) 



Frond narrow, flat, ribbon-shaped, unbranched, much attenuated at 

 base, margin somewhat crisped, sometimes so much so that the frond 

 appears spirally twisted. 



3. Yar. intestlnalis, Le Jolis. (Enteromorpha intestinalis, Auct.) 



Frond simple, attenuated, and subcompressed at base, above tubuloso- 

 inflated. 



y. Yar. compressa, Le Jolis. {Ulva compressa, L. — Enteromorpha 

 compressa, Auct.) 



Frond tubuloso-compressed, generally proliferously branched, branches 

 uniform, simple, attenuate at the base, broader and obtuse at the apex, 

 color somewhat dingy. 



Yery common all over the world, particularly in brackish water. 



This species includes the Ulva Linza, Enteromorpha intestinalis, and Enteromorpha com- 

 pressa of the Nereis Am. Bor., which can only be regarded as varieties of one species. 

 The species reaches its highest development in the var. 3 (Enteromorpha Intestinalis, 

 Auct.), which is excessively common in all shallow water along our coast, and is con- 

 spicuously disagreeable by its resemblance in shape to the swollen intestines of some 

 animal. The species approaches Ulva Lactuca, L., in var. a, which is not so common 

 an the other forms of the species whose long ribbon-like fronds are compressed instead 

 of tubular, as in var. 8. In var. y, with branching instead of simple fronds, the 



