NEW GUINEA 319 



Placostylus, the group especially characteristic of the Melanesian 

 province. 



(a) The Papuan Province. — The molluscan fauna of New 

 Guinea is the richest and by far the most original of all the 

 Australasian region. We find ourselves, almost in a moment, in 

 a district full of new and peculiar forms. New Guinea may be 

 regarded as the metropolis of the rich Helicidan fauna, which is 

 also characteristic of the Moluccas to the west, of N. and N.E. 

 Australia to the south and south-east, and of the Solomons and other 

 groups to the north-east. Here abound species of Papuina and 

 Insularia (the latter being quite peculiar), among which are 

 found, if not the largest, certainly the most finished forms of all 

 existing Helices. Chloritis (13 sp.), Planispira (5), and Cristi- 

 gibha (9) are common with the Moluccas, while a tropical 

 Australian element is shown in Pcdinogyra (1) and Hadra (4). 

 Very remarkable, too, is the occurrence of one species of Obhina 

 and Rhysota, genera which culminate in the Philippines and here 

 find their most eastward extension ; while a single Corasia serves 

 to form a link between the Corasia of the Philippines and those 

 of the Solomon Is., if the latter are true Corasia. 



We naturally find considerable traces of a Polynesian element, 

 which appears to be principally characteristic of the eastern part 

 of the island. Most noteworthy in this respect is the occur- 

 rence of Parhda (3), Tornatellina (1), Charopa (1), Tlialassia 

 (3). As compared with the true Pidmonata, the operculates are 

 feebly represented, and the great majority are of a markedly 

 Polynesian type. Not a single Cyclopliorus occurs ; Lagochilus, 

 Alycaeus, and all the tubed operculates, so marked a feature of 

 the Indo-Malay fauna, are conspicuous by their absence, and the 

 prevailing genera are Cyclotus, Helicina, and a number of sections 

 of Pupina. Leptopoma, as in the Philippines, is strongly repre- 

 sented. Not that an Indo-Malay element is altogether absent. 

 We still have Xcsta (5), Hcmiplecta (8), and even Sitala (2), but 

 the great predominance of Helix seems to have barred the pro- 

 gress, for the greater part, of the Indian Naninidae. 



The slugs appear to be represented by a solitary Vagimda. 

 A single Perrieria is a very marked feature of union with 

 Queensland, where the only other existing species (P. australis) 

 occurs. The solitary Rliytida, so far the only representative of 

 the carnivorous group of snails, emphasises this union still 



