254 ANNALS OF SCOTTISH NATURAL HISTORY 



CYLINDROCYSTIS, Meneg/i. 



1. C. Brebissonii, Menegh. General, and frequently conjugated. 



2. C. crassa, De Bary. General. 



3. C. diplospora, Lundell. Pretty common, and often conjugated. 



Orkney, Sutherland, Ross, Inverness, Aberdeen, Kincar- 

 dine, Perth, Argyle. 



Sub-sp. major, W. West (F. W. Algae of West of 

 Ireland, in " Journ. of Lin. Soc.." vol. xxix. p. 131, 

 Plate XX. fig. 5). Very scarce and rare. Aberdeen 

 only, found at the following localities on Deeside : 

 Birsemore Loch, and south of Birsemore, Dinnet 

 (where it was first found about twenty years ago, 

 and distributed as a new species under the MS. name 

 of C. ralida), Birkhill in Cromar, and Dalbagie near 

 Ballater. Length, 104-119 p.- breadth, 49-58 /JL. 



Dr. Nordstedt thought it might be reduced to a 

 form of C. diplospora, Lund., and in the absence 

 of conjugated examples it has been thought well to 

 adhere to that view for the present. It differs, 

 however, in certain points ; notably, it is more acutely 

 rounded at the ends, and is not narrowed, however 

 slightly, towards the middle. Further, there is a 

 small form, just half the size, which it was proposed 

 to name C. valida, ft minor (length, 56 /j.; breadth, 

 25 /;,). This is the counterpart, in every particular, 

 of the larger form, except size, and when seen side 

 by side in the same gathering with C. diplospora 

 it looks very different from that species. It is very 

 local and rare, but is usually to be found in some 

 quantity in Kincardine at Dalbrake in Strachan. 



COSMOCLADIUM, Brcb. 



1 . C. constrictum (Arch.), Josh. ( = Dictyosphcerium constriction, Arch.) 



-Length, 1 7-20 ^ ; breadth 10-12 /A. Zygospore globose, with 

 rather short stout spines. Diameter, ex. sp., i7-2o/x. (Our 

 Plate II. fig. 7.) Very rare. Probably often overlooked. 

 Aberdeen "Old Road "and Heughhead near Aboyne; Kin- 

 cardine Dalbrake in Strachan ; Perth Buchanty. 



2. C. perissi/tn, n. sp. Very minute ; nearly as broad as long ; con- 



striction tolerably deep and opening widely ; sides semicircular ; 

 ends rather flattened; cell-walls very pellucid, and sometimes 

 brownish in colour. Zygospore large in proportion to the 

 fronds, extremely irregular in shape, and reddish-brown in 



