190 HORN EXPRDITION — StlMMAIiY. 



{'^). A soiioR liolongiiifi; to oastorn and south-eastern Australia and Tasmania. 

 Oui- knowledge of Victorian land iiiollusca is at present unfoi-tunately Ncty 

 iiii]u'i-tVct, liiit as in other i^i-oups a fuller knowledge will douhtless re\eal a more 

 or less close alliam-e Ix^tweeu those i)f southern Victoria and Tasmania. 



In this area the species of Iladra diminish from the north to the .south, none 

 heinn' known in Tasmania; Cystopelta, Ccryodcs, and I/i'/icnrioii are couunon to 

 the mainland and Tasmania, wliile the slug Aiicifca ^^racfffi is conunon to New 

 Soutli Wales and (|)n(>ensland. The last operculate, a Jlelicina, is found in the 

 north of New Houtli Wales none being present in Tasmania, so that the trm^ south 

 eastern part of the continent is devoid of these. 



Faunal Divisions of the Australian IIecion. 



Tn his " fJeographical History of Mammals," Mr. Lydekker lias adopted the 

 name Notoga^ic llealm to include the Australian, Polynesian, Ilawaiinn and 

 Austro-Mahiyan Regions. The vVustralian llegion inchuh^s Austialia, Tnsmania, 

 New CJuinea, and the adjacent Papuan Islands. 



So far as the disti'ibution of animals and plants is concerned, in I'egard to 

 the Australian region, we have to deal with a series of events which may he 

 lirieliy sunnned up as follows: — 



(1). A division in late Cretaceous times of the land area into an eastern and 

 a western portion. 



(2). A union of these two divisions and the final formation, at all events in 

 the southern-central part of the continent of a great lacustrine area accompani(Ml 

 by more or less ]iluvial conditions, and resulting during Tertiary times in the 

 existence of a vast internal area, of which Lake Eyre may lie regai'ded as the 

 centre, suitable for the development of animal life. 



(3). Duiing this period the eastern and south-eastern coastal I'ange, then 

 probably of nuich greater height than at present, formed a barrier between ((/) the 

 eastern coastal kinds, and (/') those of the interior and west. 



(1). A land connection {a) across Torres >Straits with a Papuan area and 

 either directly or indirectly with the Polynesian region, and (J>) one aci'oss Tasmania 

 stretcliing southwaids to an Antarctic land and so allowing of communication M'ith 

 the Na^ogeic Pealm (South America). 



(o). The obliteration of the.sc two land connections ami the final isol.ilion of 

 the Austi'alian continent. 



