SANDWICH ISLANDS 327 



and obscure. Helix scarcely occurs, its place being taken by 

 small Zonitidae (^Microcystis^ Charopa^ TrocJiomorpha^ etc.), and 

 by groups of so-called Patula (^Etidodonta^ Pitys^ etc.), the exact 

 position of which is not yet settled. Libera^ remarkable for its 

 method of ovipositing (p. 128), is peculiar to the Society and 

 Hervey Is. ; Pa7'tula is almost universal, attaining its maximum 

 (40 sp.) in the Society Is. ; Tornatellina^ Pupa^ and Vertigo occur 

 throughout. 



The land operculates consist chiefly of Omphalotropis^ Piqnna, 

 Pealia, and Helicina. Piploinmatina and Palaina are abundant 

 on the Pelews, and a Moussonia occurs in the Samoa Is. Ostodes, 

 a small form of Cyclophorus^ is found in some of the southern 

 groups. The fresh-water operculates are 3Ielania, Neritina 

 (including Clithon^ a sub-genus furnished with spines), and 

 Navicella ; there are no Unionidae, while fresh-water Pulmonata 

 are very scarce. 



(h) The land Mollusca of the Hmvaiian py^ovince are distin- 

 guished by the possession of four entirely peculiar genera — 

 Achatiiiella^ Leptachatina^ Carelia, and Auricidella. ]\Iore than 

 300 of the two former genera have been described, every moun- 

 tain valley of some of the islands having its own peculiar species. 

 The destruction of the indigenous herbage by goats is rapidly 

 extinguishing many forms. Partida, and the small land oper- 

 culates, so characteristic of the other groups, are, with the excep- 

 tion of Helicina, entirely wanting. The occurrence of one of 

 the Merope group of Helix (Solomon Is.) is remarkable, and 

 there is a rich development of Succinea. " Patula,^' 3Iicrocystis, 

 Tornatellina, and the other small Polynesian land Pulmonata 

 are well represented. The presence of Isidora, absent from the 

 central Pacific groups, is remarkable, and Hrinna is a peculiar 

 genus belonging to the Limnaeidae. 



