236 ANNALS OF SCOTTISH NATURAL HISTORY 



thought by Mr. Ostenfeld to probably originate as above. 

 Mr. Ostenfeld added, that C. Hornschuchiana might be the 

 second parent if it occurred. This sedge does not, however, 

 occur on the holm, which is a very small one, and I have not 

 seen it growing near. 



*C. vesicaria, L. S. Abundant in drains running into the west end 

 of Grasswater, near Bridge of Walls. 



* Tritiaim junceum x repens. U. Sea-sands, Norwick. N. Head of 

 Sand Voe. Abundant in both places. Mr. Ostenfeld con- 

 firms the name. 



*Asplenium Ruta-muraria, L. S. On several groups of rocks 

 about the north Loch of Hostigates. 



*A. Trichomanes, L. S. Sparingly on rocks, west above Hamari 

 Water. Very sparingly on a ledge of rocks, above the south 

 side of the North Voe of Clousta. 



Polypodium Phegopteris, L. N. Exposed ledge of rock at the 

 N.W. corner of the Bjorgs of Skelberry, alt. c. 550 feet 

 Conf. 



Osmunda regalis, L. S. South Loch of Hostigates ; Burga Water ; 

 Flatpunds Loch ; Galta Water. On holms in the above lochs, 

 abundant on most. By Hostigates I found two seedlings 

 respectively ^ inch and i^ inch high. These were half-buried 

 among large stones, and had so far escaped the sheep. The 

 fern fruits very freely, and myriads of spores must be drifted 

 ashore every year, but no plants are seen on the shores of the 

 lochs. Conf. 



*Isoetes echinospora, Dur. S. Culeryn ; Burga Water ; Kirkiegarth 

 and Bardaster Lochs, Walls, and in several other lochs. 

 Apparently common in this district. 



Isoetes lacustris, L. The spores of this species are covered with 

 thin ridges, or plates, not tubercles. All our books describe 

 them wrongly, down to the last edition of Babington. They 

 are correctly described in the Scandinavian Floras. See Blytt, 

 " Norges Flora " ; and Lange, " Danske Flora." 



THE FRESH-WATER HOLMS. The examination of the Holms 

 which are scattered over so many of the fresh-water lochs has 

 especially attracted my attention during recent years, although 

 comparatively few of them have actually been visited. Whether 

 regarded as the final refuges of some species no longer known in 

 Shetland beyond their confines, or as enabling us to conjure up a 

 picture of Shetland loch-side vegetation, as it was before the advent 

 of the sheep, these holms demand our serious consideration ; and 

 until they have been more fully investigated it cannot be claimed 



