364 DESMIDE^. 



Near Manchester: Mr. Sidehotham. Dolgelly: Mr. 

 Ralfs. High Beech: A.H.H. 



A very clistinct species. The frond is usually about a 

 third less than that of Cosmarium margaritiferum. 



3. COSMARIEM ORNATUM Ralfs. 



Plate LXXXVI. Fig. 3. 



Char. Frond denticulated. Segments hroader than long. 

 Front view curved at the sides, hut 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. 



Hah. In boggy pools about Dolgelly and Barmouth: 

 Mr. Ralfs. Ashdown Forest, Sussex : 3Ir. Jenner. 

 Cheshunt Common : A. H. IL 



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

 danger of confounding it with any other liithcrto described. 

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

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

 l^eculiar to the sjjecies ; this form is occasioned by the central 

 inflation of each segment, 



4. Cosmarium orbiculatum Ralfs. 



Plate LXXXVI. Fig. 5. 



Char. Segments minute^ nearly spherical, hotli in front and 

 end vieics. 

 Cosmarium orhicidatum Ealfs, in Annals, vol. xiv. p. 392. 



pi. xi. fig. 2. 

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

 Manchester : Mr. Sidehotham. 



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



