106 THE VICTORIAN NATURALIST. 



universally distributed, abounding in both fresh and salt water, 

 certain species being peculiar to each, while certain others appear 

 to thrive in an admixture of the two, or are more abundant in 

 what we term " brackish" than in purely salt or fresh water. The 

 forms found in the sea are more numerous, are larger, and more 

 attractive, in the ordinary sense of the term, than the freshwater 

 varieties. Some species appear to be confined to certain limits of 

 latitude and longitude, while others are universally distributed 

 over the surface of the globe. Generally they would appear to be 

 more abundant in the warm and temperate latitudes than 

 further north or south, this being what one would expect. 

 They are also more plentiful in a climate like that of New 

 Zealand than upon our own continent. This naturally follows 

 upon the greater presence or absence of water and its permanence. 

 I am also inclined to think they are less abundant in our bays and 

 rivers, owing, I imagine, to the greater amount of loose sand. In 

 this I am merely giving the results of my own experience as a 

 collector, but I must now state where they may be found in so 

 far as our own immediate district is concerned. I have at various 

 times obtained excellent gatherings from Lakes Wendouree and 

 Burrumbeet, the Gong Gong waterworks at Ballarat, the Moora- 

 bool and Barwon Rivers, and also from sundry pocls and per- 

 manent waterholes, &c, too numerous to mention, in the neighbour- 

 hood of Melbourne. From the sea and brackish water I have 

 met with success at the mouth of the Yarra, Williamstown, 

 Geelong and locality, Queenscliff, Frankston, Elvvood, and 

 St. Kilda, making the circuit of the bay. In fresh water 

 such species as Surirella, Stauronia, Navicula, and Pinnu- 

 laria may be found upon the surface of the mud in lakes 

 or pools, and obtained if the water is deep by means of a 

 small dredge and line ; a pound of lead or iron being secured 

 to the line about a yard from the point of attachment to the 

 dredge, this latter merely consisting of an old mustard or jam tin, 

 which will serve the purpose quite as well as a more costly 

 apparatus. The filamentous forms are usually found attached to 

 the larger algae, sticks, stones, &c; the dirtier such objects appear 

 to the eye the more numerous the diatoms. The finer water 

 plants and weeds yield the best results, whether in fresh or salt 

 water. Such plants should not be washed in any way, but care- 

 fully raised from the water and merely drained and packed away 

 in tins or jars for treatment on arrival at home. Marine forms 

 may be obtained much in the same way as those from fresh water. 

 Sometimes the froth or foam left by the retreating waves gives 

 good results. Sand ripples and tide pools are also worthy of 

 inspection. Some collectors, too, have been successful by 

 skimming the surface of the sea with a net. Others, again, levy 

 upon the stomachs of various Molluscs, Holothurians and 



