1386 TRANSACTIONS LIVERPOOL BIOLUGICAL SOCIETY. 
probably by proximity to some iron-laden stream. These 
cockles seemed to be otherwise normal, and perfectly 
healthy. 
- In some parts of the district there is usually a filamen- 
tous brown tuft appended to the posterior (upper) end of 
the animal, which the fishermen believe to be a part of the 
body, and to be, when seen projecting from the sand, a 
sure indication of the presence of the cockle. Mr. Dawson 
drew my attention to the matter during a visit in May to 
the cockle and mussel beds in Morecambe Bay, and on 
obtaining specimens and examining them [ found that the 
tuft consisted in many cases of the zoophyte Obelia flabel- 
lata and in other cases of a filamentous Alga (sea-weed— 
a species of Sphacelaria). Both Zoophyte and Alga are 
attached to the extreme posterior edge of the valves which 
is, in the natural position of the animal, the part which is 
highest or nearest to the surface of the sand. Of course 
the tuft of Zoophyte and Alga have no special connection 
with the cockle; and their fairly constant presence in 
some localities is merely due to the circumstance that © 
the cockle shells are, compared with the sand grains by 
which they are surrounded, relatively stable objects to 
which the free swimming young stages have attached 
themselves as they would to a rock—and they have chosen 
the posterior end of the shell because that is the point 
nearest to the sea above, from which they came and into 
which they must project. There is absolutely no ground 
for the idea that the tuft is in any way injurious either to 
the cockle or to the person who eats the cockle. 
The cockle in our neighbourhood spawns in summer. 
The specimens dissected in the laboratory in June and 
July were many of them mature males and females 
with fully developed ova and spermatozoa. The number ot 
ova laid is very great, but of course a large proportion are 
