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THE LAND MOLLUSCA OF THE KEKMADEC ISLANDS. 



By Tom Iredale. 



Bead 13th June, 1913. 



PLATE XVHL 



I PROPOSE to deal with the Land Molluscs collected on Sunday 

 Island, Kermadec Group, under four headings, viz., Historical Notes, 

 Ecological Notes, Systematic Account, and General Conclusions. 



1. Historical Notes. 



In 1854 H.M.S. Herald surveyed Sunday Island, and although 

 Macgillivray collected live species of land shells which were presented 

 to the British Museum, they were never reported upon. In 1856 

 Pfeiffer described two species collected by Lieutenant Cliimmo : 

 I presume Lieutenant Chimmo was one of the officers of the Herald. 



Nothing more was heard from the Kermadecs until 1873, when 

 Mousson recorded one of Pfeitfer's species, and added three new ones 

 from a collection made by Dr. Graeife. The same year E. A. Smith 

 described a Vitrina received from Sunday Island via Auckland : this 

 was one of Mousson's new species, and Smith's name has priority by 

 a few days. 



In 1892, when Hedley and Suter made np the Reference List of 

 the Laud and Freshwater Mollusca of New Zealand, they included 

 four species only from the Kermadecs, one of Pfeiffer's species being 

 omitted. Mr. Hedley has since pointed out to me that Pfeiffer liad 

 recorded in 1863 Tornatellina Novoseelandica, Pfr., from Sunday Island. 

 The Land Molluscan fauna of Sunday Island therefore stood at the 

 end of 1907 thus— 



Helicarion Kermadecensis {^nxith) = uUima, Mousson. 



Medyla exposita (Mousson). 



Macroclilamxjs Kermadeci (Pfeiffer). 



Endodonta modicella vicinalis (Mousson). 



Helix Chimmoi, Pfeiffer, 



Tornatellina Novoseelandica, Pfeiffer. 



2. Ecological Notks. 



Sunday Island is the summit of an immense volcano, the crater 

 being about one mile and a quarter in diameter. To the north-west 

 and south-west run two long spurs which are cut into innumerable 

 deep short gullies. The crater ridge averages about 1,000 feet, the 

 highest point being over 1,700 feet, the lowest about 200 feet. The 

 two spurs are each over 1,000 feet practically their whole length. 

 The onl)' flat land on the island was a small piece on the west coast 

 and another on the east coast, though on the north coast a series 

 of terraces about 80 feet above sea-level existed. The crater was 

 similarly provided with minor ridges, the level being calculated 

 as 40 feet above sea-level. From a theoretical point of view the 

 island seemed favourable for the finding of localized races due to 

 isolation. It is densely bush-covered, has a heavy rainfall, 70 inches 



