Hutchinson — On Frcsh-ivater Shells. 207 



Art. XXII. — On the Fresh-water Shells of Bissingtcn, 



Hatches Bay. 



By F. Hutchinson, Jun. 



[Head before Hie Haivke's Bay Philosophical Institute, 26th October, 



1900.] 



Rissington is a small sheep-run situated about seventeen 

 miles north-west of Napier. It stands, as one might say, on 

 the border between the rich monotonous hills and plains of 

 the seaboard and the wilder gorge-rent uplands that lift wave 

 upon wave inland to rest at last on the stony flanks of the 

 great Kaweka Range. 



The surface-features of its 4,000 acres consist of a bold 

 limestone-crowned hill standing out from a base of the hum- 

 mocky rolling country — such a feature of the papa country of 

 this north-east portion of Hawke's Bay ; sweep upon sweep 

 of low rounded hills, drained by a network of tiny gullies feed- 

 ing the four main streams that with the wear-and-tear of ages 

 have cut great clefts lengthwise down the place — clefts wide 

 and tame in their lower courses, where they join the Manga- 

 one, a tributary of the Tutaekuri, but deepening inland into 

 the wildest of gorges, walled with great cliffs of blue marl and 

 brown conglomerate. 



The gullies of the uplands for the most part are poor in 

 springs, furnishing each its tiny creek of surface-water during 

 the winter rains, but grass-bottomed and dry in the summer 

 months. Here and there, however, a spring supplies a quiet 

 earth-bottomed stream, swampy, with still, deep pools — pools 

 loved by the poor hunted ducks when persecuted from their 

 feeding-grounds in the wide lakes and swamps of the low- 

 lands — pools that in two cases broaden out into the dignity of 

 small lakes. The main creeks of the gorges are of a totally 

 different character — wearing, tearing, turbulent shingle- 

 carriers, hurrying down over wastes of rounded pebbles that 

 ever shift and grind and pummel each other on their way to 

 feed the great shingle-spits of the coast. But one and all — 

 lakes, pools, and brawling torrents — have their quaint little 

 shelled inhabitants, from the smallest yard-wide pool of per- 

 manent water, with its score or so of univalves and bivalves, to 

 the countless hosts crawling over the mud of the lake-bottoms 

 or clinging to the water-worn boulders of the creeks. 



Now, we have in New Zealand some twenty -three species 

 of fresh-water shells, eighteen of which are univalves or spirals, 

 and five are bivalves. Of these we have on Rissington eight 



