T YND ABIDE A. 165 



broad. Sporangia usually spherical) but sometimes oval, 

 and entirely confined to the transverse tubes. 



Tyndaridea immersa, Annals of Nat. Hist. vol. xii. p. 188. 

 pi. 7. fig. 19. 



flab. Wimbledon Common : A. H. H. 



A very rare species. I have seen it but once. 



9. TYNDAKIDEA DECUSSATA Hass. 

 Plate XXXIX. Fig. 6. 



Char. Filaments of less diameter than those of the preceding 

 species. Cells usually two and a half times as long as 

 broad. Sporangia circular, and a portion of them immersed 

 either in one or other, or both cells. 



T. decussata Hassall, in Annals and Mag. of Nat. Hist, 

 vol. xii. p. 188. pi. 7. fig. 18. 



The species described by Vaucher, under the head of Con- 

 jugata decussata, would appear to be referrible to the next 

 genus, and not to Tyndaridea. 



10. TYNDAKIDEA &ALFSII Hass. 

 Plate XXXIX. Figs. 4, 5. 



Char. Filaments of less size than those of T. immersa* Cells 

 usually four times as long as broad. Sporangia elliptical, 

 their long diameter corresponding with the length of the 

 tube. 



Hob. Penzance : Mr. Ralfs. Near Cross in Hand, oppo- 

 site to where the road branches to Hailsham, and on 

 Piltdown Common. 



T. Ralfsii Hassall, in Annals of Nat. Hist. vol. xii. p. 188. 

 pi. 7. fig. 20. 



" There is not a more beautiful or elegant species than 

 this in the genus, and I have much satisfaction in dedicating 

 it to Mr. Ralfs, its first finder, and a gentleman by whom 



'M 3 



