350 transactions liverpool biological society. 

 Firth oe Lorn. 



August 2nd, N.W. of Bliaic Island, 113 fathoms. 

 This is practically the same spot as " between Kerrera 

 and Mull," July 21st, 1909, 80 fathoms, and July 24th, 

 1911, 110 fathoms. The present gathering agrees with 

 that of 1911 in being mainly a fine zoo-plankton. There 

 is, however, a small mixture of phyto-plankton, formed 

 by some neritic Diatoms, notably Eucampia zodiacus, 

 Lauderia borealis and a couple of species of Rhizosoleviia. 

 In 1909 the gathering, though still a mixture, was rather 

 more phyto-planktonic than on the other two more recent 

 occasions. On each occasion again there has been some' 

 admixture of oceanic and neritic types. In 1909 the 

 neritic predominated, and on the present occasion the 

 majority of the species are oceanic in the proportion of 

 about two to one. 



Although the Firth of Lorn is open to the Atlantic 

 to the south of Mull, the plankton does not seem to be 

 so thoroughly oceanic in its nature as that which comes 

 in north of that great island in the region round 

 Ardnamurchan. Possibly the North Atlantic drift 

 sweeps northwards from outside Islay towards the Outer 

 Hebrides without approaching the inner islands and 

 channels until it reaches the Sea-of-the-Hebrides between 

 Barra Head and Tiree, and then sends a branch inwards 

 towards the north of Mull. Such a distribution might 

 account for some of this year's observations. 



A surface gathering on August 25th in Dunstaffnage 



Bay, off the Firth of Lorn, North of Oban, shows an 



oceanic zoo-plankton with very few Diatoms and a 



few neritic animals. Most of our hauls about this 



neighbourhood* in former years had more phyto- than 



* Not, however, at quite the same locality, but further south off 

 Kerrera, Bemera and Lismore in the Firth of Lorn. 



