364 DESMIDE2E. 



Near Manchester: Mr. Sidebotham. Dolgelly: Mr. 

 Ralfs. High Beech: A.H.H. 



A very distinct species. The frond is usually about a 

 third less than that of Cosmarium margaritiferum. 



3. COSMARIDM ORNATUM Ralfs. 



Plate LXXXVI. Fig. 3. 



Char. Frond denticulated. Segments broader than long. 

 Front view curved at the sides, but truncate at the extremi- 

 ties. End view, four-lobed. 



Cosmarium ornatum Ralfs, in Annals, vol. xiv. p. 392. pi. xi. 

 fig. 3. ; Jenner, in Fl. of Tunbridge Wells, p. 194. 



Hob. In boggy pools about Dolgelly and Barmouth: 

 Mr. Ralfs. Ashdown Forest, Sussex : Mr. Jenner. 

 Cheshunt Common : A. H. II. 



This species is likewise very distinct, and there can be no 

 danger of confounding it with any other hitherto described. 

 The fronds are about as large as those of C. margaritiferum, 

 the four-lobed form of the segment when viewed endways is 

 peculiar to the species ; this form is occasioned by the central 

 inflation of each segment. 



4. COSMARIUM ORBICULATUM Ralfs. 

 Plate LXXXVI. Fig. 5. 



Char. Segments minute, nearly spherical, both in front and 



end views. 

 Cosmarium orbiculatum Ralfs, in Annals, vol. xiv. p. 392. 



pL xi. fig. 2. 



Hob. Boggy pools, near Dolgelly: Mr. Ralfs. Near 

 Manchester : Mr. Sidebotham. 



A distinct little species, and the smallest of the genus. 



