COSMARIUM. 365 



5. COSMARIUM CYLINDRICUM Ralfs. 



Plate LXXXVI. Fig. 4. 



Cha7\ Fronds small, finely denticulate. Segments longer 

 than broad, in the front view, suhquadrate, broadest at the 

 extremity, narroioer at their junction. End view cir- 

 cular. 



Cosmarium cylindricum Ralfs, in Annals, vol. xiv. pi. xi. 



f. 1. 

 Hah. Mixed with other Alga on the wet sides of a cave 



at Laurarna Cove near Penzance : 3Ir. Ralfs. 



The fronds are minute, and about twice as long as broad. 

 Segments united along their entire breadth, so that no 

 notches are formed at the sides. 



b. Fronds mostly punctated or smooth. 



6. Cosmarium crenatum Ralfs. 



Plate LXXXVI. Fig. 6. 



Cha7\ Fronds punctated. Segments broader than long, com- 

 pressed, somewhat triangular, with the margins deej)ly cre- 

 nated. End view elliiitic, 

 C. crenatum Ealfs, in Annals, vol. xiv. pi. xi. fig. 6. ; Jen- 

 ner, loc. cit. p. 196. 



Hah. Weston bogs, near Southampton, and several stations 

 in Sussex : Mr. Jenner. Near Bristol : Mr. Thwaites. 

 Near Manchester : Mr. Sidebotham, Dolgelly and Pen- 

 zance : Mr. Ralfs. 



"This plant very much resembles a young specimen of 

 C. margaritifcrum ; but as the margin is always strongly 

 crenated, even in the earliest stage, and the surfoce is punc- 

 tated and not granulated, I am induced to describe it as dis- 

 tinct." — i?a/A. 



