210 Transactions. — Zoology. 



|-in. downwards. In some parts of New Zealand it is de- 

 cidedly larger. The little brown discs are easily overlooked, 

 as they haunt the neutral-tinted reeds and raupo-stems and 

 other floating debris of our lakes, particularly as, in common 

 with nearly all fresh-water shells, they are often coated with 

 an earthy deposit — so thickly at times as to blind the inner 

 whorls completely. 



Of the common river-mussel I need say but little. We 

 can only just claim it as an occupant of Eissington : in fact, I 

 doubt if we have any living within the boundary, all I have 

 found being dead shells on the banks of the Waihau Creek. 

 A small feeder (dry in hot summers) comes into this creek 

 from one of the Ardlarsa Lakes, in which mussels are plentiful. 

 Heavy floods, raising this lake, will send a few mussels occa- 

 sionally down the feeder — dead shells, as I have said, careful 

 search having failed to reveal any living bivalves in the 

 Waihau. 



Its small ally, Pisidium novce-zelandia, our so-called fresh- 

 water cockle, will often escape the ordinary observer from its 

 small size and retiring habits. A translucent shell, varying in 

 •colour from pale-horn to nearly white, it is to be found in 

 great numbers sunk in the black ooze or gliding over the 

 :sandy mud in all our still, permanent water, in company with 

 the pond-snails, though, like them, absent from the rapid 

 shingle-bottomed streams. Our largest specimens are -Jin. in 

 length. 



Distbibution. 



Just a few words as to the distribution of these fresh- water 

 shells in Hawke's Bay. 



Taking first the river-snails, you will find them almost 

 omnipresent in all permanent water, whether rapid or 

 sluggish. Far up in the rugged subalpine gorges of the 

 Kaweka, amongst the beginnings of our rivers, I have found 

 the tiny black spirals abundant ; following down these 

 streams, in the turbulent cataracts of the middle reaches, 

 they cling in colonies round the boulders, and crawl in thou- 

 sands over the mud of the back-waters ; down through the 

 long shallow shingle-stretches as they widen out between the 

 ever-lowering hills, to shrink again to the deeper sluggish 

 channels of the plains, right down to the salt swamps of our 

 river-mouths, these shells swarm. Yes, in teeming millions 

 they fringe the quiet, reedy, bird-haunted creeks that — drain- 

 ing our Napier Swamp and the rounded sun-baked hills of the 

 seaboard — feed and fill the ever-shallowing Inner Harbour. 

 Eight down all these into water with a good strong tang of 

 the salt in it, only ceasing, in fact, as the channels burgeon 

 out into the wide mud-flats of the harbour. They get at 



