58 
ULVACEiE. 
spinelike, tlie plant becomes E. ramulosa of authors. I have seen the varieties erecta , 
ramulosa and clathrata from the American coast. The cells of which the walls of the 
frond are composed are larger and more quadrate than those of E. compressa ; the 
surface therefore looks tessellated. 
4. Enteromorpha HopJdrkii, McCalla ; frond excessively slender and byssoid, flaccid, 
very much branched ; branches feathery, decompound, erect, attenuated, set with minute 
subulate ramuli ; cellules large, hyaline, each containing one or two minute grains of 
endochrome ; the ramuli formed of a single series of such cells. Harv. Phyc. Brit, 
tab. 263. 
Hab. In rock pools between tide marks. Greenport, Mr. Hooper, (v. s.) 
Tufts very soft, 3-4 ipches long. Fronds very slender and much branched. The 
frond of this species is composed of much larger and more hyaline cells than in the 
preceding, and the endochrome is of very minute size in proportion to the cells in which 
it is lodged. This species occurs also on the shores of England and Ireland ; but is 
not so common as others of the genus, and appears to be sufficiently characterised by 
its cellular structure. The ramuli are articulated, like the branches of a Cladophora. 
IY. ULVA. L. 
Frond, membranaceous, flat, and leaflike, green. Fructification ; green granules 
(spores) often arranged in fours, dispersed over the whole frond. 
Under this generic name I still retain the species of the modern genera Prasiola , 
Viva , and Phycoseris ; the first of which differs from the second in having its cellules 
arranged in a most obviously tessellated pattern ; and the last, from either of the pre- 
ceding, by its membrane consisting of two layers of cells instead of a single layer. 
The species of the section Prasiola are of minute size, and are found in damp places, 
on the soil, on old walls and on decaying timber and thatch, &c. ; and no doubt several 
(such as P. crispa , P. calopliylla , &c.) occur in America, but I have not received any 
American specimens. Kiitzing describes a P. mexicana , Lieb. from Mexico, in words 
which would apply equally to the P. crispa of Europe. 
Sect. 1. Phycoseris ; membrane formed of a double layer of cellules. 
1. Ulva (Phycoseris) fasciata, Delile; frond stipitate, cartilagineo-membranaceous, 
rigid, cleft into several strapshaped segments, which are undulate at the margin, and 
irregularly toothed or sinuate. Del. Egypt , p. 153, t. 58, f. 5. Mont. Alg. Alger , 
p. 151, t. \\,fig. 1-2. Phycoseris fasciata, K'iitz. Sp. Alg. p. 477. Viva divisa , Suhr! 
