252 ANNALS OF SCOTTISH NATURAL HISTORY 



n. P. lagenaroides, Roy. Not common. Ross near Tain; 

 Aberdeen Slewdrum, Aboyne, Dawan, Presswhin, Dal- 

 bagie, Glen Clunie ; Kincardine Scolty Dam, Curran, 

 Bishop's Dam; Forfar Glen Clova, Glen Dole; Perth 

 Bracklin, Coilantogle. 



12. P. lamellosum (Breb.), Kiitz. Not uncommon. Sutherland, 



Inverness, Aberdeen, Kincardine, Forfar, Perth, Stirling, 

 Arran. 



13. P. Libellula (Focke, 1847), Nord. (P. closterioides, Ralfs, 



1848). Not rare. Sutherland, Ross, Inverness, Aberdeen, 



Kincardine, Forfar, Perth, Argyle. 



(3 intermedium, n. var. Precisely similar to the type, but 

 only half as large, or rather less. Length, 1 18-128 /x; 

 breadth, 253-29 /j.. This form appears to connect 

 Libdlula, Focke, with Navicula, Breb. If so, these two 

 might be supposed to be extreme forms of one species. 

 It is to be observed, however, that this new var. is 

 very uniform in size and appearance in such widely 

 separated regions as Britain and South Africa, that no 

 other intermediate forms have been noted, and that 

 the mode of conjugation of Libellula and var. /3 is 

 not known. It may be worth remarking that while 

 Navicula and this var. ft are abundant in South 

 Africa, Libellula has not been seen as yet. 



Not common may have been overlooked. Ross, 

 Inverness, Perth, Aberdeen, Kincardine, Argyle, 

 Arran. 



14. P. Margaritaceum (Ehr.), Breb., and vars. j3 and y. Common. 



Sutherland, Ross, Inverness, Aberdeen, Kincardine, Forfar, 

 Perth, Stirling, Arran, Kirkcudbright. 



15. P. niinutissimuin, Nord. Apparently rare. Ross at Poolewe ; 



Inverness at Brin ; Aberdeen at Heughhead, Aboyne, 

 with zygospores, and at " The Colonel's Bed " in Braemar. 



1 6. P. Mooreanum, Archer. Rare. Inverness near Loch Coruisk 



in Skye ; Aberdeen - - Ben-na-chie, and Birsemore Loch ; 

 Kincardine at the source of the Cowie ; Forfar Glen 

 Clova, and Clova Tableland ; Perth Forest of Athole. 



17. P. Nagellii, Breb. General. 



1 8. P. Navicula, Breb. Common, often with zygospores. Orkney, 



Ross, Inverness, Nairn, Aberdeen, Kincardine, Forfar, Perth, 

 Stirling, Argyle, Arran. 



19. P. oblongitm, De Bary. Not common. Sutherland, Ross, 



Inverness, Aberdeen, Kincardine, Forfar, Perth, Argyle, 

 Arran. 



