VAUCHERIACEJS. 121 



Plate XLVI. fig. 21. Oogonia of Vaucheria dichotoma X 100 diara. 

 Fig. 22. Oogonium X 200. Fig. 23. Antheridea X 100. Fig. 24. An- 

 theridium X 200, after Woronin. Fig. 25. Germinating spore. 



Plate J.LIX. Jigs. 5, 6. The V. submarina, Berk., generally referred 

 to this species as a variety. 



2. Vaucheria aversa. Rass.Alg. t. 6, /. 5. 



Loosely caBspitose, 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. 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, 

 " 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. or nit ho - 

 cephala " (now regarded as a variety of V. sessilis). 



Plate XLVll.,fig. 1. Oogonia and antheridia of raucheria aversa X 

 100. Fig. 2. The same X 200. Fig. 3. Mature oospore in oogonium X 

 200, after Walz. 



3. Vaucheria soricea. Lyng~b. 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, inouth 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 ornitho cephala, Ag. Sp. Alg. p. 467. Grey. 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. 



In ditches, &c. 



