VAUCHERIACE.E. 125 



6. Vaucheria geminata. (Vauch.} Walz. Jahrb. p. 147, t. 12, f. 7-11. 



Dark or dull green, in dense intricate tufts. Thallus capil- 

 lary, tough, dicliotomous. Oogonia two (rarely 1 or 3), 

 ovate or obovate, opposite, distinctly pedunculate. Antheridia 

 intermediate, subulate, more or less recurved. Mature oospore 

 spotted with brown, sporoclerm colourless, composed of three 

 strata. Sporangia on the same or a proper thallus, broadly 

 cup-shaped, truncate, and angularly horned. 



SIZE. Oospore -11--12 x -18-'19 mm. 



DCand. Fl. Fr. ii., 62. Hass. Alg. t. 3, f. 1. Cleve Vauch. 

 p. 6, f. 4. Kirsch. Alg. Schl. p. 83. Kutz. Tab. Phyc. vi., 

 t. 59, f. 3. Eng. Fl. v., 320. Harv. Man. 148. Eng. Bot. 

 i., t. 1766, ii., t. 2420. Grev. Alg. Britt. p. 193, t. 19. 

 Purton Mid. Fl. ii., 611. Johnst. Fl. Berw. ii., 252. Grev. 

 Fl. Ed. 306. Fl. Devon, ii., 56. Gray AIT. i., 291. 



Ectospenna geminata, Vauch. Conf. 29, t. 2, f. 5. 



Vaucheria Dillwyni, Rabh. Alg. Sachs. No. 1078. 



To this species we also refer the following as synonyms, 

 although usually referred to V. sessilis : 



Vaucheria ovoidea, Hass. Alg. 57, t. 5, f. 3. 

 Vaucheria ovata, Gray AIT. i., 289. 



Ectosperma ovoidea, Huds. Fl. Aug. 954. Hook. Fl. Scot. 

 979. With. Arr. iv., 129. 



In ponds and ditches. 



/ racemosa. 



Oogonia shortly pedunculate, 3 to 5 or more aggregated 

 in a corymbose manner. Antheridia single, scarcely longer 

 than the oogonia. 



SIZE. Oospore -06--08 x -075--08 mm. 



Vaucheria racemosa, Eng. Bot. ii., 126. Grev. Alg. Britt. 

 195. Harv. Man. 149. Grev. Fl. Ed. 306. Gray Arr. i., 

 292. Hass. Alg. 56, t. 3, f. 2. 



We have reproduced Hassall's figure of this form in which the antheri- 

 dium is considerably longer than the oogonia. Vaucher says, ''This 

 species is one of the most common, and is found in nearly all ditches, 

 principally in the spring. It is loaded with little bouquets manifest to 

 the unassisted sight, and which with the microscope seem to he formed of 

 a common peduncle, subdivided into pedicels, each of which carries on 

 its summit a spherical body in every way resembling the grains of other 

 ectosperms, but nearly half as small again. In the middle of this 

 bouquet is the horn, which, without doubt, performs the function of a 

 male flower, and which is here but a prolongation of the peduncle. The 

 number of grains varies from 5 to 7, but commonly 4 are met with." 



It is of this species that Hassall says, " It is most frequently infested 

 with the curious parasite Cyclops Itt-pula of Muller, which occasions the 

 growth on the filaments of such extraordinary-looking appendages, in 

 the midst of which the parasite resides." This parasite, whatever it may 

 be, was the subject of a communication by Mr. A. Lister to the Essex 

 Field Club, July 22, 1882, and will be found in the " Proceedings " of the 

 Club (Vol. iii.). 



