] 2 0 SIPHOPIIYCE^.
f
lU . :
Tlie plates for this part were all in course of printing when the above
observations were being made, so that it was too late to insert figures of
the septate threads and their contents.
Plate XLYI. Figs. 1-20. Impregnation of Vaucheria sessilis after Pring-
slieim X 200.
Figs 1-4. Stages of development of sexual organs before impregnation.
Fig. 5. During impregnation. Pigs. 6-8. The way in which the female
organ opens the cutaneous layer, bursts through, and a portion is constricted
off. Fig. 9. Approach of spermatozoids before formation of the
membrane of the embryo cell. Pig. 10. Point of female organ after
formation of the membrane of the true spore. Figs. 11-12. Later conditions
of spore after impregnation. Kgs. 13-16. Male and female
organs after impregnation. Fig. 17. Colourless spore after it is detached
from the parent tube. Fig. 18. Detached spore, which after resting three
months has become green. Figs. 19-20. Germination of the green spores.
a. TuBDLiaBEJ3, Antheridia little or scarcely hent.
1. V a u c h e ria d ic h o tom a . Lyngh. Hydro. Ban. p. 75, i. 19.
Robust, loosely cajspitose, dirty green, or becoming brownish.
Thallus very thick, setaceous, nearly a foot long, remotely
dichotomous. Oogonia sessile, globose, or ovoid, single, scattered,
or 2 to 4 to 6 approximating. Oospores, when mature,
with a triple membrane, spotted with brown. Antheridia single,
erect, oval, sub-clavate, or acute, on the same or on different
threads.—Rahh. A lg. Eur. iii. 268.
S iz e . Oogonia -1 mm. diam. Threads -2 mm. diam.
Walz in ipringsh. Jahrb. p. 152, t. xiv. f. 28-33. FL
Danioa t. 1724. Harv. Man. p. 147. Grev. Br. Alg. p. 190.
Gray. Arr. i., 289. Kirsch. Alg. Schl. p. 82. Eng. Bot. ii., t.
2418. Grev. FL Ed. 305. Mack. Hib. 233. FL Devon , ii.,
56. Kutz. Tab. vi., t. 56a. Hass. Alg. t. 4, f. 1. Eng. FL v,,
p. 319. Nordst. Bot. Not. 1879, p. 184. Jenner PL Tunb.
Wells, 176.
Conferva dichotoma, Linn. Spec. 1635. Dillw. Conf. t. 15.
Eng. Bot. t . 932. Huds. FL Ang. p. 593. Withering iv., p.
49. Hull Br. Flora, 330.
Vaucheria glohifera, De Bary Monats. 1856, p. 589. Rabh.
Alg. Ex. No. 640.
Vaucheria salina, Kutz. Tab. vi., t. 66, f. 2.
Conferva Plinii setis porcinis, Ray. Syn. 58.
Conferva dichotoma setis porcinis, Dillen. Muse. 17, t. 3, f. 9.
var. ¡3 su hm a x in a . Ag. Syst. p. 171.
Vaucheria submarina, Berk. Glean, p. 24, t. 8. Harv. Pbyc.
Brit. t. 350 B. Harv. Man. 147.
In ditches, and in brackish and salt water.
Hassell was of opinion that this species did not differ specifically from
Vauchei'ia sessilis, but the two are now regarded as belonging to different
sections. Nordstedt says that it is diteoious, but no reference is made to
this fact by Walz.
Plate X LY I. fig. 21. Oogonia of Vaucheria dichotoma X 100 diam.
Fig. 22. Oogonium X 200. Fig. 23. Antheridea X 100. Fig. 24. Antheridium
X 200, after Woronin. Fig. 25. Germinating spore.
Plate X L IX .fig s . 5, 6. The V. suhmarina, Berk., generally referred
to this species as a variety.
2 . V a u c h e r ia a v e r s a . Hass. Alg. t. 6, / . 5.
Loosely ciespitose, 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._ Oleve. Vauch. 133, 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,
“ I t 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, iu which, when the vesicles are ui 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. ormtho-
cephala ” (now regarded as a variety of V. sessilis).
Plate XLVIl.,Jig. 1. Oogonia and antheridia of Vaucheria aversa X
100. Fig. 2. The same X 200. Figi 3. Mature oospore in oogonium X
200, after Walz.
3 . V a u ch e iia so r ic ea . Byngh. Hydro. Ban. 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 produced
laterally, sessile or shortly pedicellate ; antheridia cylindrical,
or ra th e r clavate, horizontally deflexed. Spermatozoids
oblong, with a red spot, furnished with a ciliiim at each pole.
S iz e . Oogonia -1 mm. diam.
Walz in Prings. Jahrb. p. 150, t. xiii., f. 20-24.
Vaucheria ornitliocephala, A g . 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 Vauoh, p. 7.
In ditches, &c.
r