188 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Mr. Isaac C. Thompson. In 1897 a more definite scheme 

 was organised for the collection of plankton weekly from 

 six different localities off the coasts of Lancashire, 

 Cheshire and the Isle of Man ; and the material so 

 gathered was examined, and reported upon, as part of the 

 Sea Fisheries work of the district. The Annual Reports 

 of the Liverpool Marine Biology Committee and the 

 Lancashire Sea Fisheries Laboratory Reports contain, 

 from time to time, articles on the plankton of the Irish 

 Sea or scattered notices of occurrences. Thus Mr. E. T. 

 Browne, working at Port Erin from April to June, 1893, 

 noted that Ceratium tripos, C. fusus and Peridinium 

 divergens were nearly always present in his gatherings ; 

 that there was " a great decrease of Copepoda when the 

 sea is full of Diatoms " ; and that Oikopleura is 

 abundant with ova at the end of April, and that the 

 young individuals are found at the end of May. Mr. 

 H. C. Chadwick, in 1894, recorded the abundance of larval 

 and post-larval worms in May, in an article on " Plankton 

 Observations," in the Report for 1897 (p. 17). He noted 

 a great abundance of Diatoms in spring, an increase of 

 pelagic Coelenterata and Copepoda in early summer, the 

 appearance of fish-eggs and embryos and larval fish at 

 Easter, a great increase in Medusae and Ctenophora in 

 later summer, and the abundance of Dinoflagellates in 

 late summer and autumn. 



A summary account of the Port Erin plankton 

 throughout the year was given in 1899 (13th Report, 

 p. 29), and in this the maximum of Diatoms at the end 

 of March is noted, also a maximum of larval forms in the 

 last weeks in June, of Medusae in July, and of Zoeas and 

 other Decapod larvae towards the end of August. 

 Oikopleura attained its maximum that year at the end of 

 September. The presence of the three species of 



