ULVACES. 131 
Scot. ii., 91. Johnst. Fl. Berw, ii, 249. Hull, Br. Fl. 311. 
Abbot Fl. Bedf. 273. With. Arr. iv., 125. 
Scytosiphon intestinalis. Gray, Arr. i., 345. 
Enteromorpha lacustris, Hass, Trans. Linn. Soe. 
Fistularia intestinalis. Grey. Fl. Edin. 300. Fl. Devon. 
ii., 57. 
In ditches, chiefly in brackish water. 
This exceedingly variable species has many forms or varieties to which 
names have been given, one of which by rupture of the apex, is funnel- 
shaped (var. Cornucopia), others are more or less thread-like, and others 
inflated and bullate. Root a minute scutate disc. Frond from a few 
inches to one or more feet in length, and from a line to three or four 
inches, or more, in diameter; tubular, obtuse, tapering at base to little 
more than the diameter of hog’s bristle, gradually becoming inflated 
upwards, and in old age often swelling out into a large membranous 
bag, which is variously cusped and curled. Sometimes the whole frond 
is compressed and very much crisped ; substance thin and membranous, 
but not gelatinous, not closely adhering to paper in drying. Colour 
varying from a transparent yellowish green to a dull grass green; in old 
age and decay fading to adirty white. Under the microscope a portion 
of the frond exhibits the appearance of a transparent membrane covered 
with green unequal angular cells.— Harvey. 
It occurs on the sea shore, in tidal rivers, and ditches connected with 
them, whether salt, brackish, or fresh water, sometimes at a considerable 
distance from the sea. In this respect it differs from Anteromorpha 
compressa, which is not found in fresh water, and has therefore no claim 
to be inserted in the present work. 
Plate LI. figs.1, 2. Small fronds of Ent. intestinalis, natural size. 
Fig. 3, the variety Cornucopie, nat. size. Fig. 4, cells X 400. Fig. 5, 
zoogonidia, 
Genus 56. MONOSTROMA. Thur. (1854.) 
Frond plane or saccate, simple or torn and lobate, composed 
of one stratum of cells, cells somewhat rounded (sometimes 
quaternate) immersed in a homogenous membrane.—Thuret, Note 
sur la synonymie des Ulva, &c. 
This genus was formerly included in Ulva, from which it was separated 
by Thuret. See also Monograph of Monostroma, by Prof. V. Wittrock. 
The majority of species are marine. 
Monostroma laceratum. Thur. Note sur Ulv. 
Thallus membranaceous, at length free, thin and flaccid, pallid 
green, of irregular form, rugose, margin plane and eroded, or 
crisped ((04-"05 mm. thick); cells rounded, twin, ternate, or 
quaternate, disposed loosely in the intercellular substance, in 
transverse section of the thallus oval (-017--023 mm. high), 
chlorophyllose body central, of the same form as the cell, of 
which it occupies about one-half.—Wittr. Mon. Monostr., p. 
30,41, f. 2. 
Plate LL, fig. 6. Portion of frond X 200. Fig. 7, section of frond 
% 200 diam. 
