SEA-FISHERIES LABORATORY. 137 



A similar traverse made near Llanfairfechan showed the 

 following succession : — (1) Steep, stony shore. (2) Belt of 

 soft dark mud with gravelly substratum : fauna rich in species 

 and numbers. Cardium, Macoma, Littorina, Paludestrina 

 (Balanus attached to some), Arenicola, Terebella, Nereis sp., 

 and other Annelids and Nermertines, etc. Carcinus. (3) 

 Channel of shelly sand, and Terebella the chief type. (4) 

 Rippled sand 500 to 600 yards wide, a few Arenicola. (5) The 

 cockle beds (as above) with Tellina. 



The above examples, while illustrating succession, by no 

 means indicate the number of animals present. With a view 

 to gaining some information on this point, areas of one foot 

 square were marked out on various parts of different cockle 

 beds, and the numbers of the more abundant species enumerated 

 as thoroughly as possible. A few examples will be given : — 



A. Cope Scar, Priory Point, Ulverston. 6.8.1919. Sand 

 firm and fine, with a black layer beneath. Cardium, 5 (and 

 some minute young specimens) ; Macoma, 25 (average) ; 

 Paludestrina, 30 to 50 ; Arenicola, 5 to 10. 



B. Muddy zone, near Llanfairfechan, described above. 

 30.5.1919. Cardium, 14 ; Macoma, 62. 



C. " Commercial " cockle bed on Traeth Lavan. 

 27.5.1919. Cardium, 1 to 3 ; Arenicola, 1 ; Tellina (variable 

 but nowhere common). 



D. Ynyslas, near mouth of River Leri, Dyfi Estuary. 

 3.3.1919. Sand with dark underlayer. Cardium, 14 ; 

 Macoma, 60 ; Paludestrina, 70 ; Arenicola, 5 (but very 

 variable in the vicinity). 



E. Same area. 25.7.1918. Cardium, 44 ; Macoma very 

 numerous, but very young and fragile, and many broken in 

 sifting the sand) ; Paludestrina, 300 ; Arenicola, 10. 



An interesting feature at Ynyslas is the penetration of 

 Macoma and Cardium, into the Salicornetum by means of 

 streamlets or gutters which drain the area and run from one 



