COSMARIUM. 159 



SCOTLAND.- -Loch Xess, Inverness ! 

 IRELAND.- -Lough Derryad, Armagh ! 

 Geogr. Distribution.- -India. New Zealand. United 

 States. British Guiana. 



Var. elevatum West & G. S. West. (PI. LXXIX, 



fig. 6.) 



C. reniforme (Ralfs) Arch. var. elevatum West & G. S. West, Some Desni. 

 U. S. 1898, p. 307, t. 17, f. 11. 



Cells almost 1^ times longer than broad ; semicells 

 higher, with the basal angles subrectangular and the 

 lower part of the sides subparallel. 



Length 52 ^ ; breadth 36 ^ ; breadth of isthmus 

 14 ft ; thickness 24 /u. 



Geogr. Distribution.- -United States (Michigan). 



Typical specimens of this variety have not been observed 

 in the British Islands ; but a form observed from Wicken Fen, 

 Cambridgeshire, possessed the subrectangular basal angles 

 which characterize the var. elevatum (consult Gr. S. West, 

 ( Alga-H. Cambs.' 1899, p. 23). This form had a length 'of 

 54 n and a breadth of 46 ^ (PI. LXXIX, fig. 7). 



Var. apertum var. nov. (PI. LXXIX, fig. 5.) 



? C. margaritiferum (Turp.) Meneg-h. var. incisum Kirchn. Alg. Schles. 



1878, p. 150 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 198 ; ? Boldt, 



Desmid. Gronland, 1888, p. 26, t. 2, f . 28. 

 ? C. margaritiferum (Turp.) Menegli. forma istlimo elongate, Borge, 



Siissw. Chlor. Arcliang. 1894, p. 20, t. 2, f. 15. 

 ? C. Netzerianum Schmidle, Beitr. alp. Alg. 1895, p. 390, t. 15, f. 19. 



Semicells not reniform, inferior margin slightly con- 

 vex ; sinus slightly open, very gradually opening 

 outwards from a rounded apex. 



Length 56 /x ; breadth 48 p.; breadth of isthmus 19 /*. 



IRELAND. Carrantuohill, Kerry ! 



This variety differs in the form of its semicells, which, 

 owing to the open sinus, are not reniform. The granulation 

 is typical. It seems likely that both C. margaritiferum var. 

 incisum Kirchn. and C. Netzerianum Schmidle should be rele- 

 gated to this variety, but the examination of original speci- 

 mens would be necessary to confirm this suggestion. 



In outward form the semicells have a resemblance to those 

 of C. Simii Eoy & Biss. 



