366 PROCEEDINGS OP THE MALACOLOGICAL SOCIETY. 



being exactly limited. No reason whatever could be discovered for 

 this extreme localization, only about half a dozen patches being 

 observed, though every effort was made to find more. The species had 

 gregarious habits, living under rotten nikau leaves on the ground, 

 and Imndrcds could be collected from one of these patches in a few 

 hours. Neither height nor dampness was accountable for the patches, 

 one of the most vigorous patches being in a relatively dry position on 

 the sides of the cliffs only about 500-600 feet liigh. Upon the 

 highest point, over 1,700 feet, a few were obtained. These lived 

 principally under rotten logs and were of a grey colour, whereas all 

 the rest were uniformly brown. Little variability in size, shape, or 

 colour was apparent, though thousands were critically examined. 

 This is more remarkable in view of the extreme variability of the 

 close ally of the species, the Norfolk Island T. ituculpta (Pfeiffer). 



On the sides of the cliff, while cutting a path, I obtained a few 

 specimens of another Charopoid shell from under a wet moss-covered 

 stone. Upon examination it showed a fully armoured mouth, and 

 was consequently classed under Ptychodon. It was afterwards 

 commonly obtained all over the cliffs, and also rarely on the level, 

 its most frequent habitat being under dead nikau leaves, but it did 

 not despise rotten wood, and also sometimes hid itself under wet 

 stones. It was never found under dry stones like the first two 

 species mentioned. This shell I call Ptychodon pseutes. The 

 preceding five were the only snails found during the first eighteen 

 weeks, whilst our time was engaged fixing up living places, making 

 food arrangements, etc., so that it will be understood that the snails 

 were not obtrusive. 



Having cleared up the aforesaid matters vigorous search was 

 prosecuted throughout the island, with most deliglitful results. The 

 only way to establish the presence or absence of molluscs was to 

 thoroughly search the island section by section. It had been proved 

 to me by this time that the only feasible method was to search while 

 it was raining, when the snails were moving. After a couple of days' 

 search on the flat at one end, with no result, the other and untouched 

 bush-covered end Avas investigated. The bush, however, was so 

 dense that it was quite impossible to see these minute molluscs, and 

 my only chance was when a break came, which was rarely. 

 However, a piece of black bark was turned over whereon glistened 

 two minute cream Charopoids, which I feel justified in naming 

 Charopa exqiiisita. This species was afterwards found on the under- 

 sides of moss-covered stones deeply embedded in earth on the side of 

 the cliff. A few were found under dead nikau leaves on the ridge, 

 and some more were discovered under loose dry pumice-stones in the 

 crater. Only two or three were found at a time, and it is the 

 scarcest shell I obtained, the majority of the specimens being not 

 fully grown. The next day in the same place, searching among dead 

 leaves, I came across a dead shell which I call Pronesopupa senex. 

 Search as I would I could gather no more specimens that day, the 

 minute size and dark coloration effectually prohibiting its discovery 

 in the darkness of the dense bush. 



