172 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
part comparatively small and are mainly composed of 
zoo-plankton. Mr. Andrew Scott, A.L.S., who has been 
associated with us for some years in studying the 
plankton of the Irish Sea, remarked when shown some 
of the phyto-plankton samples from Canna, Rum and 
Ardmore, ‘‘ If I had not seen the locality and date on 
the bottles I should have placed them without doubt 
as Irish Sea gatherings taken in April.’’ And the 
resemblance, it may be added, is not merely in general 
appearance, but extends to the microscopic composition. 
The gatherings from Ardmore, for example, contain 
abundance of Chaetoceras (several species), Rhizosolenia 
shrubsolu and RK. stolterfothi, Lauderia borealis, 
Thalassiosira gravida and T. nordenskioldi—all of 
them Diatoms that are characteristic of an April 
gathering in the Irish Sea, off Port Erin. The abundance 
of the two species of Thalassiosira makes this and other 
July gatherings from the seas around Mull quite unlike 
a September Diatom haul in the Irish Sea, as the genus 
Thalassiosira, abundant in the North, is practically 
absent at the time of the autumnal maximum in the 
South. 
In order to demonstrate still further the characters 
of these diverse planktons, and illustrate the comparison 
between the Scottish summer series and Irish Sea 
gatherings typical of different seasons, we give here in 
tabular form the quantitative details of : — 
(A) a typical coarse zoo-plankton from off Skate 
Island at the entrance to Loch Fyne, July 18th. 
(B) a zoo-plankton of somewhat different type (with 
fewer Calanus, but many more of the smaller 
Copepoda), from Kilbrennan Sound, July 26th. 
(c) a mixed gathering, mainly phyto-plankton, from 
off Loch Ranza, Arran, J uly 27th, 
