ON SCOTTISH DESMIDIE^E 249 



of the length of nearly the same diameter, tapering a 

 little at the ends, which are expanded into rounded or 

 rotundo-truncate 'knobs' ("between the frond and its 

 apical ' knob ' there seems to be usually a more or less 

 pronounced narrow ' neck ' or contraction," p. lit.) " Suture 

 i, rarely 2, not central and often complex, of 4-7 transverse 

 striae. Membrane smooth, variable, either colourless, or 

 from pale yellow to red-brown in tint. The frond is straight, 

 or but slightly curved ; very variable in size. Endochrome 

 axillary, with a central line of corpuscles. Long., 260-489 

 p ; lat., 10-13 /JL ; lat. apic, 8.5-12.5 //." (Our Plate IV. 

 fig. 8.) 



Var. fusifonne, Turner. "Almost straight, frond not so 

 even in diameter, decidedly fusiform. Long., 295-415 

 /j. ; lat., 12.5-15 fi; lat. apic., 9-11.5 p. (Our Plate 

 IV. fig. 9.) (This species seems nearest to C. bidava- 

 tui/i, Boerg. W. B. T.) Very rare. Ross Balma- 

 carra, legit. A. W. Wills (W. B. T.) 



50. C. setaceuin, Ehr. Not so common as C. rostratum. Ross 



near Tain ; Inverness Loch Ruthven ; many localities 

 in Aberdeen and Kincardine ; Forfar Clova Tableland, 

 and Tannadice Curling Pond ; Perth Durdie, Moncreiffe, 

 Birnam, Buchanty ; Argyle near Kingshouse. 



51. C. strigosum, Breb. Rare. Ross near Tain, and Strath- 



peffer ; Inverness - - Brin ; Aberdeen -- St. Fergus Canal, 

 Mintlaw, Alford, Whitestripes, Danestone, and near Spring- 

 hill; Kincardine Lochs of Park and Lumgair. 



52. C. striolatum, Ehr. General. 



/3 orthonotuin, Roy. (F. W. Algae of Enbridge Lake, 

 Hants, in " Journ. Bot.," Nov. 1890, p. 336.) Not 

 uncommon. 



In a gathering made at about 2000 feet on Lochnagar 

 the cell-contents were observed, in numerous instances, con- 

 densed into brown, elliptical, spore-like bodies. The same 

 state has been noticed in C. directum, Arch., and some 

 others, at considerable elevations. 



53. C. sidndatum (Kutz.)* Breb.- Very rare. Inverness Brin; 



Aberdeen "Old Road," Aboyne ; Argyle head of Glen 

 Coe. 



54. C. tiirgiditin, Ehr. Not very common. Sutherland, Ross, 



Inverness, Aberdeen, Kincardine, Forfar, Stirling. 



55. C. Venus, Kiitz. Probably general. Caithness, Sutherland, 



Ross, Inverness, Aberdeen, Kincardine, Forfar, Perth, Dum- 

 barton, Argyle, Bute, Fife. 



