COSMARIUM. 137 



It seems scarcely possible to separate any form of 

 C. caelatum under the varietal name " spectabile" The figure 

 we give was taken from a Carnarvonshire specimen which 

 more nearly approached De Notarises figure than any other 

 specimen we have seen. The basal granulation of the semi- 

 cells is in the form of a broad transverse band of short, 

 almost vertical series, with from three to four granules in a 

 series. The figure given by Dr. Liitkemuller (' Desm. 

 Attersees/ t. 8, f. 8) does not appear to us to belong to this 

 variety, as it does not possess the arrangement of the basal 

 granules which constitutes the sole distinguishing feature of 

 var. spectabile. 



Var. hexagonum West. (PI. LXXVI, fig. 9.) 



Cosmarium cxlatum Ralfs var. hexagonum West, Alg. IS". Wales, 1890 

 p. 290, t. 6, f. 30. 



Cells subrectangular-hexagonal, apex truncate ; the 

 two lateral crenae of each semicell approximately 

 equal in size; granules of broad basal inflation 

 arranged in transverse and vertical series. 



Length 43-45 /x; breadth 36-38 //,; breadth of 

 isthmus 10-11 /A; thickness 25-26 /x. 



WALES.- -Capel Curig, Carnarvonshire ! 



(jeogr. Distribution.- -Germany. 



140. Cosmarium radiosum Wolle. 

 (PI. LXXVI, figs. 3, 4.) 



Cosmarium radiosum Wolle, Desm. U. S. 1884, p. 90, t. 19, f. 21-22; De 

 Toiii, Syll. Alg. 1889, p. 1052 ; West, Alg. W. Ireland, 1892, p. 159 ; 

 Nordst. Index Desm. 1896, p. 220. 



Ursinella radiosa Kuntze, Revis. gen. plant. 1891, p. 925. 



Cells of medium size, 1-| 14- times as long as broad, 

 deepty constricted, sinus narrowly linear with a 

 slightly dilated extremity ; semicells pyramidate-semi- 

 circular, sides strongly convex, apex subtruncate or 

 truncately rounded, basal angles rounded; cell-wall 

 finely granulate, granules in radiating and concentric 

 series, about 30-35 showing at the margin, and 6 or 7 

 in each radial row, gradually diminishing in size from 

 the periphery towards the centre, median basal part 

 of semicell with 8 or 9 sub vertical (somewhat diver- 



