ZYGNEMACEZ. 105 
We can recognize no plausible grounds on which the M. intricatus of 
Hassall can be maintained as a species distinctfrom M. scalaris. 
Plate XLII. fig.1. a, sterile cells % 400; 6, conjugating cells, with 
zygospores x 400. 
Mesocarpus recurvus. Hass. 
Sterile cells 5 to 10 times as long as broad. 
Zygospore globose. Sporoderm brown, even. 
Sizz. ‘012-018 mm. Zygospore 023 mm. diam. 
Hass. Alg. 168, t. 44, f.1. Rabh. Alg. Eur. iii. 257. 
Sphericarpus recurvus, Hass. Ann. N. Hist. xii. 186, t. 7, f.10. 
In ditches. 
Plate XLII. fig. 2. a, sterile cells X 400; b, conjugating cells with 
zygospores X 400. 
Sub-Genus Pievrocarrus. Braun. 
Mesocarpus pleurocarpus. De Bary Conj.p. 81. 
Sterile cells 2 to 3 times as long as broad. 
Zygospores subglobose, brown, even. 
Size. Cells 025-03 mm. Zygospore ‘03 mm. diam. 
Pleurocarpus mirabilis, Braun, Alg. Uni. p. 60. Rabh. Alg. 
iii, 258. 
Zygogonium pleurospermum, Kutz Tab. v.t 13. 
Mougeotia genuflexa, Ag. and others. Eng. Fl. v. 8360. Eng. 
Bot. Ed. 11. t. 2505. Jenner. Fl. Tunb. Wells, 182. Hass. 
Alg. 172, t. 40, f. 2. Harv. Man. 141. Mack. Fl. Hib. 231. 
Dickie Bot. Guide, 296. 
Conferva .genufleza, Dillw. Conf. t.6. Eng. Bot, Ed. 1, t. 
1914. 
Zygnema genuflecum, Johnst. Fl. Berw. ii. 257. Grev. Fl. 
Ed. 320. 
Serpentaria genuflexa, Gray Arr, 1, 300. 
var, compressus. 
Mougeotia compressa, Eng. Fl. v. p. 360. Eng. Bot. Ed. 2, 
p- 172. Harv. Man. 141. 
Zygnema compressum, Lyngb. Hyd. Dan. t. 58. 
Serpentaria compressa, Gray Arr. 1. 300. 
Pleurocarpus compressus, Rabh. Alg. Eur. iii. 258. 
In moor pools, &c. 
This widely diffused species forms vast yellowish-green masses, which 
Harvey says are often thirty feet in diameter; we have often met with 
them covering several square feet. The filaments are fragile, soon 
breaking into short lengths, bent almost at right angles and united at the 
angles, hence the old name of Mougeotia genuflexa. 
Plate XLII. fig. 1. Cells in conjugation X 400; 6, fertile cells 
with zygospore, after De Bary X 400; ¢, v, zygospores x 400. 
