60 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



specimens of this form which have been recorded from 

 British waters. I have myself (Clare Island Survey 

 Beports, Part 43, 1912) recorded a Bopyrid from 

 Porcellana longicornis, in which the males had the 

 abdomen distinctly divided up into segments, whereas the 

 males of the present specimens, as, indeed, of all species 

 belonging to the genus Pleurocrypta, have the abdomen 

 unsegmented. The Clare Island specimens probably 

 belong to an undescribed species. 

 " Amphipoda — 



" Gammarus duebenii (Lilljeborg). I found a 

 Gammarid, which I take to be this species, very abundant 

 in pools, which occur in crevices and hollows on the 

 limestone shores at Scarlet Point. These pools are 

 practically of fresh (rain) water, which may become 

 slightly brackish at extreme high tides or during storms. 

 Gnats were breeding in them freely at Easter, and 

 numbers of water beetles were noticed. Gammarus 

 duebenii was very abundant in every pool, but I am not 

 aware that it has previously been recorded from this area. 



" Caprella acanthi f era (Leach). Mr. Storey collected 

 two specimens among hydroids and sponges on the shores 

 of the Calf of Man, in the Sound." 



The Minute Life of the Sea-beach. 



In our last Report it was shown that certain 

 greenish-brown patches on the sandy beach at Port Erin, 

 a little below high-water mark, are caused sometimes by 

 vast numbers of the active little Dinoflagellate animal 

 known as Amphidinium operculatum, and sometimes by 

 equally large quantities of various quiescent Diatoms — 

 unicellular plants enclosed in delicate siliceous cases. 



During 1911, the history of this alternation of two 



