488 Proceedings of the Roijal Physical Society. 



so on tlie Durness limestone, where apparently a very 

 similar flora exists. Dry as octopetala is abundant around Dur- 

 ness, and so is Primula scotica, and the former is almost 

 equally abundant at Inchnadamph in Assynt. 



During one or two short excursions made in company with 

 the Messrs Scott of Balnakeil, whose great hospitality and 

 kindness I can never forget, I visited other portions of the 

 coast in the vicinity of Durness. At one place, a little to 

 the west of Balnakeil, and between it and the entrance of 

 the Kyle of Durness, I was shown a peculiar " swallow " or 

 creux in the level land about 200 yards from the shore. It 

 is about 90 feet deep, and the sea runs up a long chasm 

 and cave and fills the bottom. It is said that a boat 

 can pass up this chasm and through the cave in fine 

 weather. 



On another occasion we visited the far-famed Smoo Cave, 

 and I lit it up by means of magnesium wire. I do not 

 intend to describe the Smoo Cave in this place, but will refer 

 you to what is perhaps the only good description of it, by 

 my friend Dr Heddle, in the Geognosy and Mineralogy of 

 Scotland, Part viii., pages 257-262. 



During my stay at Durness, I also devoted a large share 

 of my attention to the varieties of trout found in the lochs 

 and streams of the district, and in this I was very largely 

 assisted by my friend Mr D. Mackay of Portnacon, a local 

 naturalist of talent and ability, and having an intimate 

 knowledge of the botany, geology, and zoology of the 

 country around. One of the results of these inquiries was 

 the discovery of a variety of trout, which Dr Francis Day 

 informs me, after examining specimens which T forwarded to 

 him, are more nearly related to Loch Leven trout than any 

 other link he has seen, having the coecal appendages inter- 

 mediate in number between Salmo fario and Salmo levenensis, 

 and being as silvery in appearance in the juvenile stage as 

 sea-trout. These will be found fully described in Dr Day's 

 fine new work upon British Fishes. Several other interesting 

 notes on varieties, and the success of introduction of trout to 

 Ashless lochs, etc., were noted by me; but I must not at 

 present diverge too much from the object of this paper, 



