96 Proceedings of the Royal Society of Edinburgh. [Sess. 



of the genera Cocconeis, Gomphonema, Diatoma, etc. A handful of 

 this Cladophora was taken from Loch Fitty and floated at the top 

 of a tall vessel of water. In the course of several days a considerable 

 deposit of pure diatom frustules had fallen from the Cladophora and 

 collected upon the bottom of the vessel. 



Cladophora glomerata, Klltz. Very abundant in some lochs of Areas 

 IV. and VI., covering stones and rocks from the margin to 7 feet deep. 



Mougeotia sp. Sometimes very abundant in I. and IV. 



Zygogonium ericetorum, De Bary. " I.," IV. Often very abundant in 

 water near the shores of the hill lochs. 



Zygnema Vaucherii, Ag. " I., II." It is also very frequent in lochs 

 of Areas IV. and VI. 



Porphyridium cruentum, Nag. VI. Wet mud at Barhapple Loch, ex- 

 posed tlirough drought, was in places coloured red by this organism. 



Gloeotrichia Pisum, Thur. VI. Occurred in such extreme abundance 

 as a plankton organism in Soulseat L. that the water in some of 

 the little creeks was of the consistency of liquid mud. 



Anabsena circinalis, Rabenh. VII. The water of Kinghorn Loch in 

 places had the appearance of pale green paint, due to the vast 

 quantity of this organism. It is frequently common in lowland 

 lochs. The relationship between the presence of this plant and the 

 death of certain fish, particularly perch, requires further elucidation. 

 I found numbers of dead perch around Kinghorn Loch. 



Melosira granulata, Rcdfs. VI. Occurs as a plankton organism in 

 White Loch, Castle-Kennedy, in such abundance that the discolora- 

 tion of the water (p. 143) is in part due to it. 



Dickieia and similar gelatinous Diatomaceae. " L," IV. Sometimes 

 abundant at the margins of the hill lochs. Other diatoms, of course, 

 abound everywhere. 



I have frequently found submersed plants of the higher orders 

 injured by the luxuriant growth of filamentous Algae. In Lochs 

 Skerrow and Grennoch, for example, quantities of Scapania undulata 

 were in a defunct condition through being overgrown with Ulothrix 

 sequalis, Batrachospermum vagum, Binuclearia tatrana, etc. 



The following comparative table has been arranged in order to show 

 at a glance the most conspicuous and abundant plants (i.e. those forming 

 more or less definite associations) of peaty and non-peaty lochs, together with 

 the positions they usually occupy therein. The plants have been divided 

 into seven groups, and those in each group are so arranged that the species 



