46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



again probably have even more than on the above occa- 

 sion. These considerable variations in the amount of the 

 plankton are very striking at Port Erin, and taken along 

 with the frequent presence of an organism in one part of 

 the bay and not in another, impress one forcibly with 

 the fact of the irregularity, both qualitatively and 

 quantitatively, of the distribution of plankton in our seas. 

 An instance has been noticed by the Curator in his Report 

 where he points out that Noctiluca has been abundant for 

 two years in August off the North coast of Anglesey at a 

 time when it was very rare at Port Erin. How far such 

 irregularities in distribution can really be accounted for 

 by currents, tidal and otherwise, and can be co-related 

 with the physical characters of the water, has still to be 

 worked out in detail in our district. 



Mr. Alfred Holt, junior, B.A. (Cantab.), has kindly 

 undertaken to examine for me in the Laboratory a number 

 of samples of water from various parts of the Irish Sea, in 

 order to determine how far such methods of taking the 

 densities and salinities as we can readily and rapidly apply 

 at sea or at the Biological Station are sufficiently accurate 

 and reliable. Although his work so far has been mainly 

 for the purpose of testing various methods and comparing 

 results, still it may be of interest to give here the specific 

 gravities, salinities and other chemical determinations of 

 a series of his samples, in order to give some idea of the 

 range over the district. A more detailed account of this 

 work, both as to methods and results, will be contributed 

 by Mr. Holt to the forthcoming Fisheries Laboratory 

 Report. 



