252 
PE0CEEDING9 OF SOCIETIES. 
Another form to which I would next direct attention is one in which 
I find a single, hut important, difficulty, in referring to the genus Sphse- 
rozosma, and it is the following:—I cannot find either one or two “ glan¬ 
dular processes” between the joints of the filament, the presence of which 
is one of the characters of the genus Sphaerozosma (Corda). The filament, 
which is very minute, is, however, plane and fragile; while the joints, 
which are about as broad as long, are constricted by a sharp, not deep 
notch at each side between the projecting lateral inflations at the base 
of the segments, giving a pinnatifid appearance to the margin of the 
filament, which thus possesses all the characteristics of Sphaerozosma, 
save' the one above noticed. Surrounding this form I do not think 
there exists a gelatinous sheath; but I am not able to affirm this at all 
confidently. The ends of the segments are straight and abruptly trun¬ 
cate, each in close apposition to the truncate end of the neighbour¬ 
ing joint, without the apparent intervention of any “ glandular pro¬ 
cesses” (Fig- 7).* 4 This form is very minute, and is very fragile; hence 
seldom found having more than fifteen or twenty joints in the filament, 
generally less; often one single cell only is met with. The endochrome is 
light-green, and possesses a single “ vesicle” (or corpuscle) at the centre 
of each segment. Its minute size, the absence of the conspicuous central 
solitary “gland,” its truncate and square-angled (not rounded) ends, 
and the lateral pouting projections of each joint at the base of the seg¬ 
ments, readily distinguish this form from Sphcerozosma vertebratum. It 
differs from Splicer ozosma excavatum, which it more nearly approaches 
in size, by its square ends and lateral protuberant inflations, with a sharp 
notch at the constriction at each side, and in being wider at the basal infla¬ 
tion of the segments than at the ends, not, as in Spheerozosma excavatum , 
with rounded ends wider there than at the centre, and having a deep 
wide sinus at both sides of the joint. I may add that, so far as my 
humble experience goes, the “junction-glands” of Sphcerozosma exca¬ 
vatum are often very obscure. The separated joints of the form of 
which I have tried to convey a conception, considerably resemble a 
minute form of Cosmarium, and such I thought a single joint was till 
I met it in lengthened filaments. To obviate the difficulty here met 
with, two courses may appear to be open: either to allow this plant to 
remain as an aberrant member of the genus Sphaerozosma—an unadvi- 
sable course if it could be avoided—or else to alter the characters of the 
genus by omitting the “junction-glands” as essential to it, for it appears, 
I think, that the plane or compressed filament is itself enough to distin¬ 
guish Sphaerozosma from the cylindrical or angular filamentous genera, 
* I would here remark that Sphaerozosma pulchrum (Bailey), an American species, 
is described and figured (Ralfs’ “ Br. Des.,” Appendix, p. 209, Plate XXXV., Fig. 2, 
a and h) as having straight junction-margins, connected by short bands, without any men¬ 
tion of “ glandular processes.” In the drawing the joints are represented in both figures 
as even without septa between them, giving the idea of a continuous compressed tube, 
with lateral inflations, but which in this respect is surely erroneous; but which, if drawn, 
would give a junction-margin somewhat like that described above. 
