MARINE BIOLOGICAL STATION AT PORT ERIN. 45 



the preservation and further cultivation of some sea-fisheries 

 may depend. 



Our own contributions to the subject in the Irish Sea 

 so far deal only with a few of the shore and shallow-water 

 animals, and Miss Catherine Mayne, B.Sc, in several visits 

 to Port Erin has given me much assistance in counting and 

 measuring and weighing the more abundant animals and 

 plants, and in preparing a series of diagrams showing the 

 areas occupied by selected species on a typical square foot 

 on different parts of the shore. Some of these data were 

 made use of in a paper printed this year by the Linnean Society 

 (" Spolia Runiana IV "), from which I may take as examples 

 the following three very abundant animals, all free-swimming 

 when young but fixed in the adult condition, and all of value 

 as food of marketable fishes : — ■ 



(1) The gregarious polychaet worm Sabellaria alveolata, 

 which builds masses of sandy tubes on the rocks at Hilbre 

 Island and elsewhere, and where 40 square yards may contain 

 over a million worms (See fig. 1, p. 51). 



(2) The common rock-barnacle Balanus balanoides, from 

 the base of Bradda Head at Port Erin, where there may be 

 about 3,000 barnacles on a square foot of rock (Fig. 2, p. 53). 



(3) The edible mussel Mytilus edulis, the most abundant 

 and most generally useful mollusc in our seas. The rocks 

 at Hilbre Island and elsewhere may be covered with a layer of 

 young mussels which are so closely placed as to be absolutely 

 continuous, while Professor Johnstone has calculated that a 

 mussel-bed in Morecambe Bay may have 16,000 young mussels 

 to the square foot, and may produce per unit of area nearly 

 a hundred times the amount of flesh for food that is produced 

 by cultivated land (Fig. 3, p. 56). 



My object in referring to these still incomplete investi- 

 gations is to direct the attention of our students and local 

 naturalists to what seems a natural and useful extension of 



