during the process of overlaying it seems more than likely that 

 the track would be washed away. 



Hantzschel: In my lecture 1 mentioned the slimy material only briefly. 



Trails of Nereis are often consolidated by slime and those of 

 Arenicola by ferruginous material. Yesterday we saw the same 

 phenomenon on the beach of Sapelo Island in the burrows of 

 Callianassa. 1 think this must be a prerequisite for consolidation 

 before becoming a fossil. 



Redfield: May 1 comment on your question? Some years ago I was inter- 



ested in the subject of marine fouling and one of the things which 

 seems to happen almost immediately when any object is placed 

 in the sea is that it becomes coated with a slimy material which 

 is a film of microbial origin. I have often wondered if films of 

 that type were not only present as they must be around all par- 

 ticles of sand, if they did not tend to compact and bind together 

 and give the sand a structure which it would not have if it were 

 perfectly clean, and so add to the permanence of traces of this 

 sort. 



McHugh: I was interested in your remark about Littorina, how various 



individuals will follow each other along in the same path. I was 

 interested this afternoon to watch some of them on the mud flats 

 and to see how exactly one will follow the path of another and 1 

 wonder how they can do this. 1 was wondering about the mech- 

 anism by which he senses that another one has gone before him. 



Hantzschel: I don't know. 



Davis: Did you find more trails in calcareous muds than you did in non- 



calcareous ? The reason for asking that is because carbon diox- 

 ide given off by the body of the animal will help cause induration 

 of sediments if you have calcareous material. 



Hantzschel: The sediments of the tidal flats of the North Sea are mostly 



sandy, more sand and more clay, but no calcareous material. 



Zeigler: Have any studies been made of the amount of area on a flat which 



is turned over per tide by these trails and the amount of sediment 

 which is stirred up? 



Hantzschel; It is difficult to say. I think we have no quantitative data on this. 



Chronic: Have any studies been made of the impressions of the bottom 



which algae or floating organisms might make in shallow water - 

 say tidal flats ? 



Hantzschel: These are things which we don't call traces but which in Germany 



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