EUASTRUM. 383 



at each side, and suddenly contracted to form the very short 

 neck ; the terminal lobe has each side elongated and rounded 

 entire in a and slightly emarginated in /3; the terminal 

 notch is very obscure. The transverse view is twice as long 

 as broad, with two rounded projections at each end, and three 

 on each side, and a small central opening at the original 

 junction-point of the segments." — Ralfs. 



7. EUASTRUM CIRCULARE Hass. 



Plate XC. Fig. 5. 



Char. Frond about twice as long as broad, small, smooth ; 



each segment anteriorly occupied with seven tubercles. Jive 



at the basal, and two at the distal extremity, four of the 



five basal tubercles disposed in a half circle around the fifth. 



Hah. High Beech : A. H. H. 



A very distinct little species. 



b. Segments icith acute angles, sometimes prolonged into spijwus 

 processes not generally tubercidated. 



8. EUASTRUM ROSTRATUM Halfs. 



Plate XCI. Fig. 8. 



Char. Basal lobes of the segments broad and emarginate. 

 Terminal lobe icith a curved acute spine-like process on 

 each side. 



Euastrum rostratum Ralfs, in Annals, vol. xiv^ pi. vii. f. 5. 



Hab, In freshwater pools near Dolgelly : Mr. Ralfs. 



" Frond very minute, about twice as long as broad ; seg- 

 ments obscurely three-lobed, or rather with a broad base, 

 which is emarginate on each side, and then contracted into a 

 broad short neck, connecting it with the terminal lobe. The 

 terminal portion has on each side a curved subacute tubercle 

 or process, somewhat like a beak; the end of the lobe is 

 prominent, generally angular, with a deep rounded terminal 

 notch."  



