COSMARIUM. 363 



Infus. p. 196. f. 126.; Bailey, Amer. Bacil. in Am. 

 Journ. of Sciences and Arts, vol. xli. No. 2. p. 295. fig. 8. 

 Ursinella margaritifera Turp., Diet, des Sc. Nat. (1820). 

 Heterocarpella Ursinella Kiitz., Syn. Diatom, p. 598. 

 Cymbella reniformis Ag., Consp. Diatom, p. 10. ; Grev. 

 in Hook. Br. Flor. vol. ii. p. 415. ; Harv. Brit. Alg. 

 p. 215. Cosmarium margaritiferum Ralfs, in Annals of 

 Nat. Hist. vol. xiv. p. 393. pi. xi. fig. 4. ; Jenner, in 

 loc. cit. p. 194. 



Hob. In bogs and pools, &c. common; Weston bogs, 

 near Southampton, and numerous habitats in Sussex 

 and Kent : Mr. Jenner. Farnham, Surrey : Mr. Reeves. 

 Cheshunt, Herts : A. H. H. Near Bristol : Mr. Thwaites. 

 Barmouth : Rev. T. Salwey. Dolgelly, Carnarvon, and 

 Penzance : Mr. Ralfs. 



This species varies considerably in size, form, and in the 

 number and degree of developement of the spines, which 

 cover the frond. Each segment may be compared in form 

 to a kidney. It is the most abundant species of the genus. 

 Ehrenberg figures the denticles as placed in regular series 

 or rows, which in some specimens I have seen to be the 

 case. 



2. COSMARIUM BOTRYTIS Menegh. 

 Plate LXXXVI. Fig. 2. 



Char. Frond denticulated, compressed. Segments truncato- 

 triangular. End view elliptic. 



C. Botrytis Meneg., Synop. Desmid. p. 220. Euastrum Bo- 

 try tis Ehr., Infus. p. 163. tab. xii. fig. 8. C. Botrytis 

 Ralfs, in Annals of Nat. Hist., vol. xiv. pi. xi. fig. 5. 

 Heterocarpella Botrytis Bory, in Diet. Classique, 1825. 

 Euastrum angulosum Ehr., Infus. tab. xii. fig. 8. Cos- 

 marium deltoides, in part, Corda, Almanac, de Carlsbad, 

 1835, p. 205. 



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



