62 CONTRIBUTIONS FOR SYSTEMATIC CATALOGUE AQUATIC SHELLS 



Poiamopyrgns antipodum (tlie Amnicola antipochcm of Gi'ey, 

 vide Dieffenbach's Now Zealand, 1843), a form of extreme 

 variability iu the outline of its shell to the species described by 

 Quoy and Gaimard, so abundant in almost all the sluggish 

 streams of this island. 



I also describe several apparently new species that iu all 

 probability belong to the same grouj), but in most instances 

 the opportunity of a careful examination of the animals has 

 not occurred. 



Several species I pui'pose placing iu a new sub-genus, and 

 add one or two others, but with no little hesitation, as in 

 most cases the animals have not been examined. 



In the genus Limncca a great amount of confusion has 

 been caused, principally by the well known general variability 

 of all the members of the family, and also from the fact that 

 an European form — the L. j^cregra — has been acclimatised, 

 the young immature shells of which have been mistaken for 

 an indigenous species, and also that one observer has confused 

 it with an undoubted native kind. 



I think I shall be able to show that we have at least four indi- 

 genous species, one of which at least has been placed in a genus 

 that has been established upon malacological chai'acters. I 

 have known for many years that the species referred to — L. 

 Launct'stonensis — Tenisoii-Woods, was really an Ampliipcplea, 

 with the lobed mantle extending over a portion of the shell. 

 Professor Ealph Tate has described a species under the name 

 of A. papijvacea (Trans. Eoyal Soc. of South Australia, 1880) 

 from Penola, S. Australia, and more recently recognised 

 several examples in a collection of aquatic shells, forwarded 

 him by Mr. K. M. Johnston, mostly obtained from the Huon 

 River (see " On the community of species of acquatie pul- 

 monate snails between Australia and Tasmania." Pro. 

 Royal Soc. Tasmania, 1884, pages 214-17.) Upon careful 

 examination of a very numerous series of examples from 

 many localities, I feel confidant that this species with the L. 

 Lazinceeioncnsieiind L. Huoncjisis of Tenison-Woods, slvq simply 

 variations of one common form, apparently well dispersed 

 over tliis island. The shells show a limited variation within 

 certain well-defined limits, but the animal is invariably 

 constant. This at once sets at rest the idea that one or other 

 of the above-mentioned forms was identical, or a variation 

 of the introdiiced Limnoea jicregra of Europe. 



The three new speeics of true Limnwa were obtain<'d in 

 localities that })reclude <he supposition of having been 

 introduced, and their form totally separates them from their 

 congeners already known to exist hero, or in any part of 

 Australasia. They show considerable specifie difference in 

 both outline of shell and form of animal ; in habit also they 

 are wide apart, two being confined to pure limped streams, 



