LOUISIADES AND SOLOMON ISLANDS 



321 



Land and Fresh-water Mollusca of the Aru Islands 



Xesta . . . 

 Microcystis 

 Hyalinia (?) . 

 Trochomorpha 

 Patula . . . 

 Eulota . . . 



1 Chloritis 



1 Cristigibba 



1 Albersia 



1 Papulna 



1 Pupa . . 



1 Stenogyra . 



Planorbis . 

 Segmentina 

 Melania 

 Leptopoma 

 Moussonia . 

 Realia . . 



1 Cyclotus 



1 Helicina 



14 Cyrena . 



3 Glaucomya 



1 Batissa . 

 1 



The Louisiades^ the d'' Entreeasteaux^ and Trohriand Is., and 

 Woodlark J., are closely related to New Guinea, containing no 

 peculiar genera. Each group, however, contains a considerable 

 proportion of peculiar species, an indication that their separation 

 from New Guinea dates from a very distant period. From the 

 Louisiades are known 34 species in all, 22 of which are peculiar. 



The fauna of the Admiralty Is., of New Hanover, and New 

 Ireland is markedly Papuan, without any especial feature of 

 distinction. The Admiralty Is. contain 15 sp. Papuina, 7 

 Chloritis, 1 Planispira, and 1 Corasia. A single Janella shows 

 relationship with the New Hebrides and with New Zealand. In 

 New Ireland Planispira (which is specially characteristic of W. 

 New Guinea and the Moluccas) has disappeared, but there are 7 

 Papuina and 6 Chloritis. The essentially Polynesian Partula 

 is present in both groups. 



The prominent feature of the Mollusca of the Solomon Is. is 

 the extraordinary development of Papuina, which here cul- 

 minates in a profusion of species and singularity of form. The 

 genus is arboreal, crawling on the branches and attaching itself 

 to the leaves of trees and underwood. Of the 140 land Pulmo- 

 nata known from the group, no less than 50, or 36 per cent, are 

 Papuina. Ten species of Corasia occur, but whether the shells 

 so identified are generically identical with those of the Philip- 

 pines, is not satisfactorily determined. Trochomorpha, with 22 

 species, here attains its maximum. Chloritis begins to fail, but 

 still has 3 species. Indo-Malay influence still appears, though 

 feebly, in Hemiplecta (3), Xesta (1), and possibly even Mac- 

 roehlamys (1). The Rhytida, the 3 Hadra, and possibly the 

 Paryphanta represent the Australian element. The growing 

 numbers of Partula (13), the small and inconspicuous land 

 operculates (only 22 in all, with Helicina very prominent), and 

 the almost complete absence of fresh-water bivalves, show signs 

 of strong Polynesian affinities. An especial link with the New 



