312 FKESli WATER ALG.'E OF LLSMORE DLSTUICT^ 



algal and infusorial) is characteristic of the district, just as the 

 predominance of the diatoms is of the river. Not a sign of the 

 Phytheliem was seen, though repeated gatherings were made from 

 shallow meres on grassland, which are said to be their favourite 

 haunt. Out of a total of 119 forms of Chlorophycece from swamp 

 and river, only 20 were common to both. 



Phceophycece. — The absence of Dinohryon, which was remarked 

 in the river, is noticeable also in the swamp-waters. Only two 

 small fragments were observed. Syiiura was plentiful. Chloro- 

 moiias, as usual, frequently present in gatherings but always 

 sparsely discributed. The most interesting item in this Class, 

 iiowever, is the discovery* of a large and handsome flagellate 

 resembling Volvox, but corresponding in structure and charac- 

 teristics more to my new genus Volvulina in the Volvocacect. 'J'o 

 receive this form, it has been necessary to propose a new genus 

 of Syngeneticce, to which I have given the name Tessella. 



Desmidiacem. — The desmids attain to the respectable total of 

 156 for the whole district, including the river; but, in no case, 

 were they found in abundance. I am inclined to attribute this, 

 as also the deficiency of Frotococcacecc, to the character of the 

 soil, which is a fine loam, very deep, so that water does not lie 

 very easily, and the surface dries very rapidly. Most promising 

 lagoons here yie'd next to nothing in the way of desmids, while 

 in the Parramatta district and the coastal district of Sydney 

 (Botany, Coogee, Centennial Park) where the soil is clay, or sand 

 with rock underlying at no great depth, little patches of swampy 

 ground, where water lies regularly after rain, will often yield a 

 certain set of desmids in profusion. It is noteworthy that the 

 desmids of the river are almost entirely dilierent from those found 

 on land. Out of 156 forms, only 17 are common to both, and of 

 these 1 1 are varieties of Closterinm, a genus whose forms seem 

 to flourish equally well in ahnost any habitat. The 116 forms 

 noted on land represent 13 genera, but only the very commonest. 

 Netriuni, Tetmemorus^ Sphce?'uzosma, Phyinatodocis, and Triplo- 

 cevas even were not observed. The absence of the last is re- 



* Or rather re-discovery, for 1 noted it tirst in Sydney, on August JsL 

 1909. 



