30 PROP, W. A, HERDMAN : COMPARISON OF SUMMER PLANKTON 



Again, tlie six hauls taken in Loch Hourn, off the Sound oli Sleat, a little 

 further up the coast, and the three taken in the closely adjacent Loch Nevis 

 are all very much alike in character, but differ from those o£ Mull ; 

 consisting, as they do, o£ small catches o£ zoo-plankton composed mainly o£ 

 small Copepoda, some young Nyctiplianes, Sagitta, Polychset larvas, a few 

 Peridinians, and many Tintinnidee. 



The gatherings taken inside these neighbouring lochs in the mainland 

 contrast markedly wiih hauls taken at the same time of year in the open 

 sea further west, e. g., off the Islands of Canna and Rum. 



A vertical haul from 85 faths. on July 19th, 1910, between Eigg and 

 Rum, and another on July 14:th, from 128 faths., between Canna and Rum, 

 show well-marked green-coloured phyto-plankton ; and other hauls off 

 Canna on July 13th and 14th in the same year, from depths of 80, 105, and 





Z\ ^^ 



i%u^ i^>-r • '^^'^"^ 





JO*, 



Fig. 5.— .\ typical Phyto-plankton Fig. 6.— A typical coarse Zoo-plankton 



gathering: from a photo-micrograph {Calanus) : from a photo-micrograph 



by Mr. Edwin Thompson. by Mr. Edwin Thompson. 



130 faths., are also characteristic phyto-i)lankton gatherings composed chiefly 

 of common species of CJicetoceros. 



The contrast between such a green Diatom haul taken in Ihe sea of the 

 Hebrides off Canna, in July, and a similarly captured haul at the entrance to 

 Loch Fyne at the same time of year is most marked, the first being a typical 

 line phyto-plankton (such as fig. 5) and the latter a typical coarse zoo- 

 plankton (fig. 6). As I shall show below, two such gatherings if obtained 



