VAUCHERIACE.Z. 121 
Plate XLVI. fig. 21. Oogonia of Vaucheria dichotoma xX 100 diam. 
Fig. 22. Oogonium x 200. Fig, 23. Antheridea X 100. Fig. 24, An- 
theridium X 200, after Woronin. Fig. 25. Germinating spore. 
Plate XLIX. figs. 5,6. The V. submarina, Berk., generally referred 
to this species as a variety. 
2. Vaucheria aversa. Hass. Aly. t. 6, f. 5. 
Loosely cespitose, sparingly branched, expanding in all 
directions, organs of fructification similar to those of V. sericea, 
but with the thallus much thicker, the oogonia larger, and sub- 
erect, now and then somewhat pedicellate ; oospores much 
smaller, 
Hass. Ann. Nat. Hist. xi. (1843), p. 429. Walz in 
Prings. Jahrb. p. 151, t. 13, f. 25-27. Cleve. Vauch. 1383, f. 7. 
Vaucheria rostellata, Kutz. Tab. vi., t. 58, f. 4. 
In ditches. 
Hassall describes this species as ‘‘ Capsules usually in pairs, and in the 
form of a bird’s head, with the beaks averted from each other. Sporangia 
circular, not entirely filling the cavity of the capsule.” To this he adds, 
“It is one of the best marked, and most peculiar of the genus, the beaks 
of the capsules being turned in opposite directions, at once distinguish it 
from all other known species, in which, when the vesicles are in pairs, 
they are directed towards each other. This averted position of the 
capsules renders the existence of a distinct horn or anther essential for 
each. In the form of the seed-vessels and in the circumstance of the 
sporangia not filling the entire cavity, the species resembles V. ornitho- 
cephala” (now regarded as a variety of V. sessilis), 
Plate XLVI1., fig.1. Oogonia and antheridia of Vaucheria aversa X 
100. Fig. 2. The same X 200. Fig. 3. Mature oospore in oogonium X 
200, after Walz. 
3. Vaucheria soricea. Lyngb. Hydro. Dan. t, 21, B. 
Tufts densely interwoven, yellowish, dirty green, or becoming 
brownish ; thallus thin, loosely and vaguely branched ; oogonia 
2 to 6 in a series, one sided, oblique oval, rostellate, mouth pro- 
duced laterally, sessile or shortly pedicellate; antheridia cylin- 
drical, or rather clavate, horizontally deflexed. Spermatozoids 
oblong, with a red spot, furnished with a cilium at each pole. 
Size. Oogonia ‘1 mm. diam. 
Walz in Prings. Jahrb. p. 150, t. xiii, f. 20-24. 
Vaucheria ornithocephala, Ag. Sp. Alg. p. 467.  Grev. Alg. 
Br. p. 193. Harv. Man. p. 148, Rabh, Alg. Exs. No. 1100. 
Nordst. Bot. Not. 1879, p. 184. 
Vaucheria polysperma, Hass. Ann. Nat. Hist. xi. (1843), 
429. Hass. Alg. t. 6,f.6. Kutz. Tab. vi, t. 58, f. 5. Rabh. 
Alg. Exs. No, 1375. Cleve Vauch. p. 7. 
Tn ditches, &e. 
