COSMAIIIUM. 233 



1892, p. 129, t, 3, f. 11; Eoy & Biss. Scott, Desm. 1894, p. 102, t. 1, 

 f. 11 ; Nordst. Index Desm. 1896, p. 135 : West & G. S. West, Alg. S. 

 England, 1897, p. 489 ; G-. S. West, Alga-ft. Cambr. 1899, p. 218. 

 C. (rregrorn var. papilliferum Gutw. Flor. Grlon. Okolic Tarnapola, 1894, 



p. 98, t. 3, f. 34. 



C. subprotumidum Nordst. var. Gregorii (Eoy & Biss.) W. cV- G. S. West, 

 Alga-fl. Yorks. 1900, p. 77 ; Alg. X. Ireland, 1902, p. 39. 



Creiiations more distinctly bioTannlate than in the 



. o 



type, marginal granules sometimes prominent and 

 conical in form ; central grannies somewhat reduced, 

 generally in 3 vertical series of 3-4 grannies in each 

 series. 



Length 23-29 ,< ; breadth 21-27^; breadth of isth- 

 mus 6*3-8 n ; thickness 12-15*5 ft. 



ENGLAND. Brothers' Water. Westmoreland! Eonnd- 

 hay Park, Leeds, W. Yorks ! Pihnoor, X. Yorks ! 

 Hornsea Mere, E. Yorks ! Sntton, Sntton West Fen, 

 and between March and G-uvhirne, Cambrido-eshire ! 



f 



Pnttenham Common, Surrey ! Slapton. Sands, Devon- 

 sliire ! 



SCOTLAND.- -Iron Hill, Banffshire ; Collieston and 

 Castleton, Braemar, Aberdeen ; Loch Lnndie, Perth ; 

 Wigtown (Eoy $ Bissetf). 



IKKLAND. Louefh G-artan, Donegal ! ISTear West-port 



O ~ JL 



and near F oxford. Mayo ! 



)'. Distribution.--Gsi\.icia in Austria. 



It is quite impossible to separate C. G-regorii as a species 

 distinct from C, subprotumidum, and we imagine that Messrs. 

 Rov and Bissett. and also Gutwinski. must have entirely over- 



t. 



looked the latter when they published descriptions and figures 

 of the former. 



The var. Greqorii differs only in the slight reduction of the 



U / 



central protuberance (and its attendant granules) and in the 

 more conspicuously bigranulate marginal crenations. 



Schmidle has recentlv described an African Desmid under 



* 



the name of " C. occultnin' (consult Schmidle, ( Alg. aus 

 Nyassa-See/ 1903, p. 69, t. 1. f. 25) which appears to us to 

 be scarcely separable from some of the forms of C. subpro- 

 tumidum, but his published figure is not very good. It should 

 also be remembered that C. subprotiimidtim is known from 

 three localities in Central Africa, one of which is on the 



/ 



margin of Lake Xyassa (consult G. S. West, f Alg. Third Tan- 

 ganyika ExpediV 1907, p. 121). 



