338 Mr. J. Ralfs on the Nostochinez. 
drospermum, by availing myself of the greater radiating capacity 
of the former. 
The filaments, as in the other genera, have at first all their 
joints uniform, but the terminal joint at each end soon enlarges 
into a vesicular cell, which is either orbicular, elliptic or’ovate, 
and is generally furnished with fine scattered hairs or fibres : the 
penultimate joints then elongate and become cylindrical, after- 
wards they increase considerably in breadth, and when mature 
are always elliptic or elliptic-oblong. Sometimes two or even 
three sporangia are formed between the vesicular and the ordinary 
cells. The additional sporangia however are not uniformly pre- 
sent even in filaments from the same stratum, and are sometimes 
double at one extremity and not at the other ; in fact, few mature 
specimens can be examined without observing examples of these 
variations. Hence, although the doubling of the sporangia oe- 
curs more abundantly in some specimens or species than in others, 
I cannot rely upon it as a specific distinction. 
There can be no difficulty in recognizing this genus under the 
microscope. ‘The filaments, especially when only one extremity 
is visible, are remarkable for their animal-like appearance. The 
chain of ordinary cells resembles a slender-jointed body; the 
enlarged elliptic sporangium, at least twice as broad as the re- 
mainder of the filament, represents the thorax, and the head is 
mimicked by the vesicular cell, which, in colour, shape and ge- 
neral aspect, differs from the other cells, whilst the presence of 
fine hairs renders the imitation more perfect. 
It will thus be seen that the terminal cells are invariably vesi- 
cular, the penultimate ones always become sporangia, and the 
central ones remain unaltered. 
When the filaments break up, the sporangia separate from the 
ordinary cells, but remain for some time crowned by the vesi- 
cular ones. The filament in Spherozyga frequently breaks at the 
vesicular cells, after which the portion retaming one attached to 
its sporangium, appears, at first sight, to belong to this genus. 
In the recent state however the slightest attention will show its 
true character, for the vesicular cell of the broken Spherozyga 
retains the punctum or globule at each end, which is not the 
case in Cylindrospermum, as it is only present where another cell 
has been conjoined. t 
1. C. catenatum ( ). Filaments moniliform ; ordinary joints or- 
bicular ; vesicular cells oval ; sporangia oval, catenate. 
This species was probably gathered in South Wales, but I 
omitted to note the habitat when the specimens were preserved. 
Stratum bluish green ; filaments very fine, elongated, straight 
or slightly flexuose, generally parallel. Ordinary cells orbicular, 
