62 THE VICTORIAN NATURALIST. 



Another characteristic feature is the presence of black sand on 

 the surface of the dry watercourses. It will be found that this is 

 magnetic, and can be gathered in quantities with a magnetized 

 knife-blade. The mineral is magnetite, and is derived from the 

 basalt. 



In some places, as on the Saltwater, behind the racecourse, the 

 pliocene fossiliferous beds are overlain by the newer basalt which 

 forms the great western plain of the colony. 



The material carried down by the stream has helped to form 

 the great estuary deposit of Batman's Swamp. The fossils found 

 here are all, I believe, recent, though some, like Area trapezium, 

 are now rare where they were then plentiful. The new dock cut- 

 ting, till recently filled with water, formed an excellent collecting 

 ground for specimens. 



Owing to the numerous road-cuttings that have been made since 

 the publication of the geological quarter-sheet, which embraces 

 the area I have spoken of, it will be found that numerous minor 

 corrections will have to be made in the boundaries of the various 

 deposits. 



I am afraid that, in condensing my observations, I have had to 

 omit a great deal of important and interesting matter, but I hope 

 that those who wish to learn more of the valley will go there, 

 hammer in hand, day after day, and study it for themselves. 



AN AFTERNOON'S POND HUNTING. 



By J. Shephard. 



{Read before the Field Naturalists' Club of Victoria, i \th August, 



1890.) 



Six weeks ago I went out to visit the ponds in the vicinity of 

 Brighton, in search of microscopic organisms, not expecting to 

 find much of interest, owing to the wet and stormy weather, 

 which I feared would have filled the pools with muddy water. 



On returning home to examine the takings, I found, among 

 other animals, a profusion of a species of rotifer, new to me. It 

 was a large specimen, being quite visible to the naked eye when 

 the bottle containing it was held up to the light. Examined with 

 a magnification of fifty diameters, it presented the appearance of 

 a transparent flexible bell, the mouth being fringed with rapidly 

 vibrating cilia. There was a red spot on one side of the mouth ; 

 below, the beautiful transparence of the outer case allowed a full 

 view of the interior structure. Immediately underneath the red 

 spot — or so-called eye — there was a pair of sickle-shaped jaws, 

 which occasionally opened and shut to slice up some particle of 

 nutriment brought in by the vortex created by the lashing cilia ; 

 the jaws were at the entrance of a tubular cavity, passing down- 



