.PALUDINA. 



V 



general form, which we hesitate not to assert, can scarcely 

 be considered a sufficient distinction ; wherefore, upon 

 mature deliberation we are now disposed to unite with 

 Paludina all those shells which have hitherto been regarded 

 as AmpuUarice, which have an horny operculum, retaining 

 in Ampullaria only those whose operculum is testaceous. 

 This will cause a great dismemberment of the Genus 

 Ampullaria as now received, and consequently show, that 

 we have been misled in uniting the Planorbis Cornu-arietis 

 of Lamarck to Ampullaria when it ought to have been 

 joined to Paludina. The two Genera must nevertheless 

 be considered as very closely allied. The Paludinae are 

 all freshwater shells as far as we know, and they may be 

 regarded as evidence of the fresh-water origin of the 

 Petworth Marble which abounds with them. We believe 

 none of them to be aestuary shells, but there are some 

 species found in the aestuaries of iNew South Wales which 

 have the general form and appearance of Paludina?, but 

 which differ however in the operculum, which in these is 

 spiral, with few volutions, and approaches to that of the 

 Neritee ; these are typified in what are commonly called 

 the upper marine formations (that of Ileadon Hill being 

 undoubtedly an aestuary formation) by various species 

 peculiar to these formations, which have been variously 

 placed by Conchologists, probably on account of their 

 ignorance of the operculum, some having placed them 

 with Ampullaria, others with J^atica, &c. We have 

 represented at fig. 5 and fig. 6 in our plate, a recent and 

 fossil species of this remarkable connecting Genus in order 

 that Geologists may have an opportunity of recognizing it. 



Paludinae are not peculiar to any climate, but are 

 found in tropical as well as in temperate latitudes; the 

 fossil species abound in a thin bed immediately above the 

 upper freshwater bed at Headon Hill, also in the Petworth 

 Marble. The Genus has been called Vivipara by some 

 authors. We have several recent species in England and 

 throughout Europe ; others are abundantly produced in 

 rivers, ponds, and lakes in the West India Islands, in 

 South and North America, in China and other eastern 

 countries. 



