VI PREFACE. 



Falkland, South Georgia, Kerguelen, and Marion Islands ; Chione 

 Stutchburyi Kerguelen ; C. mesodesma Tristan da Cunha. 



Of the non-marine Mollusca, Potamopyrgus has a remarkable 

 distribution, extending from Australasia to tropical America and 

 west Africa, whilst Melanopsis occurs in New Zealand, New 

 Caledonia, Spain, north Africa, and Asia Minor. The Austral- 

 asian genus Gundlachia occurs also in North America and on 

 the Antilles. Curiously enough, Succinea has never been recorded 

 from New Zealand, the 8. toitientosa, Pfeift'er, being a Limnoea, 

 In the collection of shells left by the late Mr. Traill there 

 were a few specimens of a Succinea which, I believe, were 

 found in New Zealand. I sent a specimen to Mr. Edgar A. 

 Smith, of the British Museum, and he informed me that it 

 was unlike any form known to him. Not being quite certain 

 whether Traill' s specimens were really collected in New Zealand, 

 I refrained from describing them. Of the Phenacohelicidce, the 

 genera Phacussa, Thalassohelix, Allodiscus, and Flam-muUna are 

 also found in Tasmania, the second and third also in Australia, 

 and some nearly allied forms occur on Lord Howe Island and 

 in New Caledonia. Flammulina has spread to Lord Howe, 

 Norfolk, and the Caroline Islands ; it is most likely an antarctic 

 genus, being allied to Aniphidoxa and St&phanoda of South 

 America, and. less so, to Tmchycystis of South Africa. The 

 Australasian-Polynesian genus Endodoitta has quite recently been 

 discovered in Natal ; Afrodonta, Melvill and Ponsonby, is very 

 near the subgenera Thaumatadon and Ptychodon ; and undoubted 

 species of Charopa have also been found, the animal and the 

 dentition having been examined by the writer. The subgenus 

 Helenocoiiritti from St. Helena I take to be nearly allied to the 

 New Zealand subgenus Ptychodon. The subgenus Phrixgnathus of 

 the genus Laoma occurs also in Tasmania and Australia. The 

 fresh-water genus Diplodon, generally known under the name 

 of Unio, is widely distributed in South America, New Zealand, 

 the northern rivers of Tasmania, Australia, and one species is 

 recorded from the Congo River, Africa. Highly interesting 

 from the geographic standpoint is the discovery of Strutkiolaria 

 papulosa at the Seychelles : and the occurrence of ( 'ryptoplax 

 striatus, Lam... a Ckitoti found from Torres Strait to Tasmania (but 

 not in New Zealand), at Zanzibar, Khor, Dongola, and Natal. 



