94 TRANSACTIONS LIVEKPOOL BIOLOGICAL SOCIETY. 



lighter particles remain afloat depends largely upon the 

 strength of the current that carries the material along. 



Practically the whole of the Lancashire coast-line is 

 influenced more or less by the outpouring of large rivers, 

 such as the Dee, Mersey, and Eibble in the southern and 

 central part, and by all the rivers flowing into Morecambe 

 Bay in the north. Therefore, unless we can go to a con- 

 siderable distance from land, our tow-net collections 

 are almost wholly composed of vegetable debris, the 

 land origin of which is clearly demonstrated by the 

 presence of sporangia of ferns, seed capsules and leaves 

 of mosses, protecting scales of leaf-buds, twigs and leaves 

 of trees, etc. 



The quantity of debris present in these local tow- 

 nettings is, of course, subject to weather and tidal 

 influences. After a spell of calm, during neap tides, we 

 occasionally get a gathering nearly free from rubbish. 

 One or two gatherings from the vicinity of the Bar Light- 

 ship in the Mersey consisted almost entirely of the 

 Copepod Eurytemora. In the summer of 1895, gatherings 

 were taken in the Bock Channel, which contained nothing 

 but large quantities of Noctiluca. This was unusually 

 abundant throughout the southern part of our district for 

 a few weeks, occasionally giving the water a distinct 

 brown appearance. None of the gatherings taken in the 

 Barrow Channel, outside of Walney Island Lighthouse, 

 have been free from debris, and the same is true of those 

 taken in the Bibble, off Lytham Pier, and in the neigh- 

 bourhood of Nelson Buoy. Mr. Ascroft's system of 

 placing his tow-nettings in white dishes with clean sea 

 water, and allowing the organisms to separate out and 

 come to the sides of the vessels, where they are secured 

 and preserved, is a very useful one, but, unfortunately, 

 not always practicable by our fishery officers, as their 

 police work takes up most of their time. 



