48 BRITISH DESMIDIACE.K. 



apex 10-14 /* ; breadth of isthmus 8-12 /x; thickness 

 10-5-14 /*. 



ENGLAND. Near Bowness (Bissett), and Helvellyn !, 

 Westmoreland. Ogden Clough, Holden Grhyll near 

 Keio-hley, Penyghent, and Cowgill Wold Moss, Widdale 

 Fell, W. Yorks^! Mickle and Cronkley Fells, N. Yorks ! 

 Chippenham Fen, Cambridge ! Enbridge Lake, Hants 



WALES. Ffestiniog and Llyn-an-afon, Carnarvon- 

 shire ! 



SCOTLAND.- -Ross, Inverness, Banff, Aberdeen, Kin- 

 cardine, Forfar !, Perth !, and Stirling (Roy $ Bissett). 

 Orkneys ! 



IRELAND. Ballynahmch and Loch Annierin, Gal- 

 way ! Slieve Donard, Down ! Dublin and Wicklow 

 (Archer). 



Geogr. Distribution.- -France. Germany. Austria 

 and Galicia. Italy. Norway. Sweden. Bornholm. 

 Poland (var.). Faeroes. Xova Zembla. Spitsbergen. 

 Greenland. United States. 



C. anceps is a very characteristic alpine and subalpine 

 species,, occnrring associated with C. Holmiense, C.tetragonum 

 var. Lundellii, C. speciosum, C. galerituiu, C. oclitliodes, and 

 certain other species, among mosses on the dripping rocks of 

 mountain glens, and in the boggy springs high np on the 

 mountains. In West Yorkshire it is generally found on the 

 dripping sandstone and grit rocks in the ghylls and glens, and 

 also in the springs on the Millstone Grit above the limestone. 

 A curious anomaly in its distribution was its abundant occur- 



/ 



rence in August, 1898,, in a ditch in Chippenham Fen,. 

 Cambridgeshire. 



C. anceps is nearly allied to C. decedens, from which it can 

 be distinguished by its somewhat smaller size, its narrower 

 apices with less prominent apical angles, and by the straighter 

 (less retuse) sides of the semicells. 



G-utwinski (' Nonn. Alg. Nov./ 1896, p. 43) has described a 

 "forma punctata" and a " forma angusta' of this species, 

 but the latter form is scarcely deserving of a special name as 

 the relative proportions of this species are variable within 

 limits which would include such a form. 



