592 JAMES BURTON ON HYDRODICTYOX RETICULATUM. 



away. In that case the ' breaking of the meres ' would be an 

 annual occurrence, or nearly so, with more tendency to regularity 

 than it seems to have. Clearly there must be some simultaneous 

 occurrence of several favourable circumstances which does not 

 frequently arise : possibly some special type of weather and 

 some narrow range of temperature at a particular season would 

 be factors in the required conditions." 



Jottrn. Quekell Microscopical Club, Ser. 2, Vol. XII., No. 77, November 1915. 



