24 The Scottish Naturalist. 



340 pusillus L. Loch of Kirbuster, B. 



341 pectinatus L., B. Loch of Kirbuster, Loch of Harray. Very 

 common in Harray and Birsay, J. W. H. T. 



342 filiformis Nolte., B. Loch of Harray, Fidge, Swanbister Mil 

 Pond, Pond at Hoxa Links, S. Ronaldshay. No doubt else 

 where. 



/ subjoin here a copy of notes on Orcadian Potamogetons by 

 Mr. Arthur Bennett, F.L.S., sent by him to me. 



Pota?nogeto?i filifor?nis, Pers. (Nolte !) 



"Swanbister, Orkney, 1852, J. Boswell." 

 "Loch of Harray, Dr. J. W. H. Trail, 1876." 

 " Bridge of Broigar, L. of Harray, 1880." 

 This last approaches P. fasciculatus Wolfgang, of which I have a 

 specimen from the author. 

 P. heterophyllus Schreb. 



" In a ditch of running water between Kirkwall and Strom- 

 ness, Orkney, Sept., 1873, J- T; Boswell." 

 P. heterophyllus Schreb. 



" Kirbuster Loch, Orphir, Orkney, July, 1875, J. T. Bos- 

 well, form with broad bared submerged leaves." 

 This answers to Swedish specimens of P. intermedins Tis., " ad 

 interim." 

 P. nitens, Weber. 



"Birsay, Orkney, August, 1876," Dr. Trail. 

 This is a remarkable plant, but seems best placed under nitens. 

 It has the stem much branched, with elongated peduncles. 



P. Crispus L. is not mentioned in these notes by Mr. Bennett, but I sent him 

 specimens, which he said were correct. — W. I. F. 



P. nitens, Weber. 



" Loch of Harray in ' Bay of Islands,' Orkney, August, 



1873," J. T - Boswell. 



I believe this is correct : it is of course widely different from the 



curvifolius If ait., and comes between Weber's type and var. 



latifolius, Tis! 



P. prcelongus, Wulf rv\.<gnX. occur. I have it from "Yarrow's Loch, 



Caithness." 

 P. perfoliatus, L. 



" Loch of Stennis, Orkney, August, 1876," Dr. Trail. 

 A small elegant form. 

 P. pusillus, L. 



