108 BRITISH DESMIDIACE.E. 



Var. angusto-sinuata Gay. (PI. L, fig. 5.) 



M. denticulata var. angusto-sinuata Gay, Monogr. loc. Conj. 1884, p. 52, 

 t. 1, f. -i; West, Alg. Eng. Lake Distr. 1892, p. 722. 



Cells more angular than in the type, with all the 

 incisions closed and very narrow ; subdivisions of lateral 

 lobes variable, generally retuse and rounded. 



Length 260 //, : breadth 186 ft; breadth of isthmus 

 30 jit. 



ENGLAND. Loughrigg, Westmoreland ! 



SCOTLAND. New Galloway, Kirkcudbright ! 



Geogr. Distribution. France. 



This variety should perhaps be placed as a synonym of 

 var. angulosa. It includes those angular forms in which the 

 incisions are closed and linear. It is no doubt much more 

 generally distributed than is indicated by the localities, but 

 has been overlooked. 



Var. notata Xordst. (PI. L, fig. 6.) 



M. denticulata var. notata Nordst. in Bot. Notiser, 1887, p. 155 ; Freslrw. 

 Alg. N. Zeal. 1888, p. 29, t. 2, f. 13 ; Roy and Biss. Scott. Desm. 1893, 

 p. 174; West & G. S. West, Alga-fl. Yorks. 1900, p. 67. 



Polar lobe with a pair of small teeth on each side 

 of the median notch ; semicells from the vertical view 

 with slightly-undulate margins and with a prominent, 

 somewhat acute papilla at the middle on each side. 



Length 232-282 ^; breadth 200-220 //,; thickness 



ENGLAND. Terrington, X. Yorks ! 



SCOTLAND.- -Not uncommon (Roy fy Bissett). Suther- 

 land ! 



Geogr. Distribution. Germany. Sweden. Finland. 

 New Zealand. 



This variety may also have a much wider distribution than 

 is here indicated. 



Var. subnotata West. (PI. L, fig. 7.) 



M. denticulata var. sultnotata West, Alg. Eng. Lake Distr. 1892, p. 722, 

 t. 9, f . 5. 



Polar lobe with a small tooth on each side of the 



