Mr. J. Ralfs on the Nostochinez. 335 
DoticuosrerMuUM, Thwaites MS. 
Filaments simple, generally moniliform, aggregated into a gela- 
tinous stratum ; sporangia interstitial, elongated, separated 
from the vesicular cells by the or dinary joints. 
Dolichospermum differs from Spherozyga only in the different 
arrangement of its cells. In the latter genus the vesicular cells 
connect the sporangia, whereas in the former they are situated 
amongst the ordinary cells. 
The sporangia are much elongated and mostly cylindrical. 
They are developed from the ordinary cells, which are more or 
less remote from the vesicular ones. Mr. Thwaites finds that 
their extremities are invariably truncated, and the endochrome 
escapes in an undivided mass, a circumstance he has not noticed 
in the other genera belonging to the Nostochinee. 
This genus is distinguished from Cylindrospermum by the in- 
terstitial position of the sporangia and vesicular cells, and from 
Trichormus and Spermosira by its elongated sporangia. 
1. D. inequale ( ). Filaments moniliform; ordinary cells at first 
quadrate, finally orbicular; vesicular cells large, spherical; sporangia 
linear, catenate. P 
Boggy pools. Dolmelynlyn near Dolgelley, J. R. 
This plant forms extensive strata, composed of thick gelatinous 
masses of a deep green colour. Filaments elongated, consisting 
of from 100 to 200 cells, and, being stouter than in most species 
belonging to this family, visible to the naked eye. Ordinary cells 
distinct, quadrate in immature specimens, but at length nearly 
spherical, appearing punctate on account of the scattered gra- 
nular matter which they contain. Vesicular cells spherical, 
broader than the ordinary joints and occurring at short intervals. 
Sporangia three or four times longer than broad, with truncate 
ends, in chains of from two to five members. 
Dolichospermum inequale may be known from the following 
species by its spherical vesieular cells and catenate sporangia. 
PuaTE IX. fig. 1. 
2. D. Ralfsii (Kiitzing). Filaments moniliform ; ordinary joints 
spherical ; vesicular cells elliptic ; sporangia elliptic or cylindrical, 
one or two in each series. Cylindrospermum Ralfsii, Kiitzing, Bot. 
Zeitg. (1847), p. 197; Species Algarum, p. 293; Tabule Phyco- 
logicee, t. 98. fig. 7. 
Bog and rivulet at Llyn Gwernan near Dolgelley, J. R. 
Dolichospermum Ralfsii occurs in extensive strata of a velvety 
rich dark green colour, sometimes verging towards xruginous 
green. A portion placed in water threw out, in the course of one 
