Mr. Hassall^s Notices of British Freshwater Alga. 187 



Sph. remrvus ; cells about six times as long as broad, not usually 

 reciu-ved ; sporangia circular and smaller than those of Sph. re- 

 curvus. Fig. 12. 

 Hab. Hertford Heath. 



Sph. parvulus. For description see ' Annals and Magazine of 

 Nat. Hist.' vol. xi. ; and for figiu*e, PI. VII. tig. 13 and M. 

 Sjih. avails. Filaments about equal in size to those of Sph. par- 

 vulus-, cells ten or twelve times as long as broad; sporangia 

 slightly elliptical, their long diameter being placed in the di- 

 rection of the length of the cells. See fig. 15. 

 Hah. Wimbledon Common. 



The sporangia, although elliptical, are not near so much so as 

 are those of Sph. depressus, and the filaments arc not one-half so 

 large. 



Sph. angustns. Filaments much more slender than those of Sph. 

 par^'ulus; cells very many times longer than broad; sporangia 

 circular, veiy large in comparison vnih the size of the filaments. 

 Fig. 16. 



Hab. Penzance, Mr. Kalfs. 



This is a very distinct species, and for its discovery we are in- 

 debted to Mr. Ralfs. 



Genus Tyndaridea. 

 The species of the genus Tyndaridea may with great propriety 

 be placed under two heads. Under the one should be arranged 

 all those species in which the sporangia are formed within the 

 cells, while under the second head those species should be placed 

 in which the sporangia are lodged in the transverse tubes. 



Vaucher, in his description of Tyndaridea pectinata, thus inge- 

 niously, though I fear not satisfactorily, endeavom's to account 

 for the formation of sporangia in the transverse tubes : — " Les 

 grains sont entierement spheriques et un pen herissees, ce qui sans 

 doute est la cause pom- laquelle elles sont retennues dans le canal 

 de communication qui est entre les deux tubes." — Vaucher, p. 78. 

 I have now to describe fom* fine species belonging to this second 

 division of the genus Tyndaridea, 



* Sporangia lodged in the transverse tubes. 

 Tyndaridea conspicua. Filaments of considerable diameter ; cells 

 about one and a half or t-^^ce as long as broad ; endochrome di- 

 stinctly stellate ; sporangia large, cu'cular, and partly immersed 

 in the cells. See fig. 17. 

 Hab. Wimbledon Common. 



This species bears considerable resemblance to Vauchei-'s figm'e 

 of T. pectinata ; however, I do not think that it is that species, for 

 I presume that Vaucher employed the same magnifying power to 



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