SEA-FISHERIES LABORATORY. 301 



where it may be subjected to the action of the air and 

 water, these worms are playing an important part in the 

 removal of products, which, if left to accumulate, would 

 soon become objectionable. 



The number of worms, and therefore of castings, 

 varies considerably in different sands. Davison* has given 

 an account of observations made in August, 1891, on the 

 Holy Island sands. He counted the castings in nineteen 

 measured areas, and found that the smallest number in 

 any one of these areas was 8'2 per square yard, while the 

 largest number was 42 per square yard. In both cases the 

 castings were fairly large. In other two of these nineteen 

 areas, Where the castings were very large (their average 

 weight, when dried, being three ounces and two and a 

 quarter ounces respectively), their numbers were 11 and 

 14*5 per square yards respectively. 



At Musselburgh, on the Firth of Forth, there are 

 extensive sands laid bare at low tide in which the sub- 

 jacent layer contains a moderate amount of organic 

 matter. Here worms and castings of large size are 

 abundant near and for some distance above low-water 

 mark. There are (January, 1904) about twelve to fifteen 

 large castings per square yard, the average weight of 

 (eight of) which when dried is three ounces. In the 

 course of a few minutes seven fine worms, the mean length 

 of which was thirteen inches, in addition to other smaller 

 ones, were obtained here. Although these sands have been 

 visited almost daily for a long period of years by fishermen 

 in search of bait, there seems to be no scarcity of worms, 

 although probably over a thousand per day are, on an 

 average, obtained. 



Near Portobello the beach near low water is gravelly 

 in parts, and castings are scarce, but higher up the beach, 



* Geological Magazine, Vol. VIIL, 1891, p. 489. 



