BY G. 



PLAYFAIR. 



95 



Flora. 



Alo.k. Richni. Nepean. Yan Yean. Afr. L. Scottish L. 



Chlorophyceae 57 60 25 43 31 



Desmidiacese 57 112 61 19 102 



Bacillariese 134 48 19 58 38 



Myxophycese 38 19 4 36 16 



Phytheliese 16 ... 2 



Algal Fcnqi. 



Chytridiacese 6 not noted. 



Schizomycetes 13 



305 255 109 158 187 



Dinobryon nil 



Peridinieae 



Vermes 



Tardigrada 



Entomostraca 



Rotatoria 14 14 



Infusoria 34 35 



Rhizopoda 33 13 



"93 "84 



Plankto7i.— Aiter my experience of the Nepean water, in 

 which the Phytheliece and Feridiniece were so remarkably well 

 represented, it was disappointing to find them both absent from 

 the Richmond. This was the case with Rhizosolenia and 

 Di^iohryon also. 



Desmidiacece. — The Desmid flora seems to me to be extra- 

 ordinarily rich, in face of the decided preponderance of the 

 Diatomacece, the number of forms being almost equal to that of 

 the Yan Yean plankton with only 19 diatoms. Of the 57 forms 

 noted, exactly half belong to the genus Cosmarium (29), and a 

 little more than one-quarter to Clostenum (15); Goriatozygon 1, 

 Docidium (Pleur.) 2, Peiiium 2, Micrasterias 2, Euastrum 1, 

 Staurastrum 5, make up the remainder. One is prepared for 

 the absence oi Xanthidium, the forms of that genus being priu- 



