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CONTRIBUTIONS TO A KNOWLEDGE OF THE 

 BIOLOGY OF THE RICHMOND RIVER. 



By G. I. Playfair, Research Scholar of the University of 

 Sydney in Hydrobiology and Plankton. 



(Plates ii.-viii.) 



The material which has given occasion for the following notes 

 was obtained from the Richmond River and tributary creeks, 

 principally in the neighbourhood of Lismore, during the spring 

 and summer of 1912-13. Lismore lies on the North arm of the 

 river at the head of the navigable portion, and my richest gather- 

 ings were made in the short stretch of river, almost undisturbed 

 by traffic, between the bridge and the boatshed. Here, on either 

 side, were to be found huge beds of weed, chiefly MyriophyUum 

 and Elodea, many yards in extent, and reaching right up to the 

 surface of the water. The river remained undisturbed by heavy 

 rains from the end of September, 1912, to the beginning of Feb- 

 ruary, 1913, and the current being very slow indeed, the surface 

 of these weed-beds became increasingly rich in both plant and 

 animal life. Upon two occasions gatherings were made with 

 silk plankton-nets, but these proved disappointing, nothing being 

 obtained but Coscincdiscus lacustris and a few other diatoms, 

 and as the weed-beds themselves constituted a very efficient filter, 

 it was determined to rely altogether upon them. 



On the main river, a single sample was obtained at Casino, 

 near the bridge, three mucous strata from the river-brink at 

 Coraki, and a stripping from a small bunch of weeds in a tribu- 

 tary creek at Kyogle. 



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