112 
idia (sBojJ. in diam.) and smaller nuclei (300// long) with only six striae, 
collected by Prof. Macoun, Canada, Pacific R.R. survey, west of the 
Saskatchewan, August, t88i. With all these dififerences I do 
not, however, feel warranted in giving either form a distinct name, 
since the general habit of the plants seems the same, namely, the 
short leaves and rays, the persistently three-celled and not attenuated 
terminals, the equally stipitate antheridia, similar sporangia and 
nuclei with varying striae, in both sharp and slightly prominent. 
Other forms will doubtless be discovered which will enable us to 
group them with greater certainty. 
In my plants the sporangia are numerous in the fundus of the 
verticil, both without and within the base of the leaves; but, on the 
fertile node of the leaf, they are regularly disposed on the ventral as- 
pect, two, with the intermediate, rather long-stalked antheridium, 
while there are regularly three leaflets or rays on the dorsal aspect. 
The coronula is evanescent, and the ends of the enveloping cells of 
the sporangium are swollen (Plate Fig. 4). Mr, Pringle's plants 
have mature fruit in April (the usual time for T. g/omera/a), and 
Prof. Macoun's are in their prime in August. This fact, together with 
the much larger antheridia and rather smaller nuclei of the latter, 
with only six strise, may prove sufficient to distinguish the forms as 
distinct sub-species. Further collections are needed. 
ToLYPELLA coMOSA, nov, sp, — Minor, monoica, statura 0.05- 
o.io"*\ color incrustatione cinerascens. Folia verticillorum ster- 
ilium indivisa, 3- articulata, fertilia in capitula congesta, sunplic- 
iter divisa, radiis 3- cellularibus, obtusis, non attenuatis. Sporangia 
in divisura foliorum et in fundo verticilli aggregata ; coronula evan- 
escente; nucleo atro, ovali 425-475 p- long., 320-360 lat., 7-8- gyrate, 
striis prominulis, obtusis. Antheridia sessilia, 400-425 // diam. 
This plant is allied to the European T. nidifica^ Leonh., from 
which it differs in its fresh water habit, smaller size, smaller anther- 
idia and persistent coronula. It is thickly incrusted, having a grey- 
ish color even when first taken from the water, and is quite fragile. 
The fertile whorls are compact and compound, from numerous short 
axillary shoots. The leaves of the sterile verticils are simple, long, 
and have three segments. The fertile leaves have a short basal seg- 
ment, then a fertile node consisting usually of three leaflets of un- 
equal length, and three fruiting cells on the ventral aspect ; these 
produce, usually, two sporangia and one intermediate antheridium, 
but occasionally we find two antheridia and one sporangium. The 
central cell is, however, always an antheridium, and the latter is sessile 
or nearly so. The lateral leaflets are longer than the dorsal leaflet ; 
the terminal division of the leaf, above the fertile node, is elongated, 
2-8™™^, and three-celled. These numerous elongated leaflets clothe 
the plant as with hairs, hence the specific name comosa. The first 
segment of the leaflets is the longest, and the terminal segment usually 
the shortest. The diameter of the leaf, below the fertile node, aver- 
ages 300// (in T. nidifica^ 400/'), of the terminal segment near the 
tip loo//, (in 7iidifica, 190/^.) Tlie main stem, below the first fertile 
verticil, averages 360/1 in diameter. The primary verticil consists 
of seven leaves with some adventitious leaflets and sporangia, which 
