104 MANUAL OF THE MOLLUSCA. 



cipally to East Australia. He notices, Helix 133, Vitrina 17, 

 Succinea, 12, Bulimus 17, Pupa 6, Balea 1, and others belonging 

 to genera Triboniophorus, Limax, and Planorbis. 



13. South Austkalia and Tasmania. 



From extra-tropical Australia "we have the following : — 

 Helix 9, Helicarion 2, Bulimus 2, Succinea 1 (common to Swan 

 Eiverand Tasmania), Limax olivaceus, and one Ancylus. Two 

 of the largest land snails. Helix Cunninghami and Falconeri, are 

 found in New South Wales. The coasts of this region are 

 thinly wooded, but much of it is rendered desert by want of 

 rain ; in New South Wales droughts recur at intervals of twelve 

 years, and sometimes last three years, during which time scarcely 

 any rain falls. 



14. New Zealand. 



The moist and equable climate of these islands (which have a 

 mean temperature of 61° — 63®) is favourable to the existence of 

 numerous land-snails. Nearly 100 species of land and fresh- 

 water shells are already determined, and are all peculiar ; the 

 genus Helix musters 60 species, some of which, including the 

 great H. Busby i, resemble in shape the European Helicellae ; 

 Bulimus 3, Balea (peregrina), Vitrina 2 of peculiar form, Tor- 

 natellina 1, Cyclophorus cytora, and Omphalotropis egea. 

 There are two slugs, Limax antipodarum and Janella bitenta- 

 culata ; two fresh-water pulmonifera, Physa variabilis and Latia 

 neritoides ; several marine air-breathers, — Oncidium {Peronia) 2, 

 Siphonaria 3, Amphibola 1 {avellana). The other fresh- water 

 shells are Melanopsis trifasciatus (a Lusitanian type), Assiminea 

 antipodarum and Zelandise, Amnicola ? corolla, Cyclas Zelandise, 

 and Unio Menziesii and Aucklandicus. 



Vitrina zebra is found at the Auckland Islands. 



15. Polynesian Eegion. 



The Pacific Islands are partly the volcanic summits of sub- 

 merged mountain ranges, usually fringed or surrounded with 

 coral reefs ; and partly atolls or lagoon islands, scarcely rising 

 above the sea, and presenting no vestige of the rock on which 

 they are based. The low coral islands form a long stream of 

 archipelagos, commencing in the west with the Pelews, Caro- 

 lines, Radack, Gilbert, and Ellice groups, then scattered over a 

 wider space, and ending eastwards in the Low Archipelago : 



