Mr. HassalPs Notices of British Freshwater Algcs, 187 



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



recurved ; 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 figure, PI. VII. fig. 13 and 14. 



Sph. ovalis. 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 are not one-half so 



large. 



Sph. angustus. Filaments much more slender than those of Sph, 

 parvulus ; cells very many times longer than broad ; sporangia 



circular, very large in comparison with the size of the filaments. 



Fig. 16. 



Hab. Penzance, Mr. Ralfs. 



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 peu herissees, ce qui sans 

 doute est la cause pour laquelle elles sont retennues dans le canal 

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



I have now to describe four 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 twice as long as broad ; endochrome di- 

 stinctly stellate ; sporangia large, circular, and partly immersed 



in the cells. See fig. 17. 



Hab. Wimbledon Common. 



This species bears considerable resemblance to Vaucher's figure 

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

 I presume that Vaucher employed the same magnifying power to 



02 



