Art. XXII.—On the Land Mollusca of Little Barrier Island.
[Read before the Auckland Institute, 7th October, 1901]
In the Christchurch Press of the 21st November, 1892, some notes on Little Barrier Island were published re the visits of Messrs. Henry Wright and Boscawen, of the Lands Department, the notes being probably quoted from the New Zealand Herald. There occurs the following passage: “He (Mr. Boscawen) also found the pupurangi, or New Zealand snail (Helix busbyi), which is about 4 in. or 5 in. long, and lays an egg like that of a bird.” It is curious that Mr. Shakespear, the curator of Little Barrier Island, has never found this large snail, nor has Mr. Cheeseman, on his repeated visits to the island, come across it. Possibly Mr. Boscawen's specimen was “the last of the Mohicans.” Be this as it may, the fact remains that up to the end of the last century nothing else was known about the land molluscan fauna of Little Barrier Island
In January last Mr. J. Adams, of the Thames, was paying a visit to the island, and, knowing him to be a very good collector of land-shells, I asked him to have a good look out for these mostly minute and inconspicuous creatures. On Mr. Adams's return he kindly handed over to me the harvest of his collecting, which enables me now to publish the first list of land-shells from this our native reserve. To Mr. Adams I wish to express my gratitude for the great trouble he has taken to get this nice and interesting collection together. No new species were amongst these shells, which belong to four genera and represent twelve species. There is little doubt but that further collecting will produce many additions to the list.
(1.)Rhenea coresia, Gray.
Distribution.—North Island only, but more common in the northern part of it. It is not uncommon in the bush near Auckland, and occurs also on Chicken Island.
(2.) Flammulina (Allodiscus) urquharti, Suter.
Distribution,—This minute brown shell is, no doubt, easily overlooked; and, on the other side, it must be mentioned that all the species of the subgenus Allodiscus are not common shells at all. The type was found on Mount Pirongia, and specimens from the Hunua Range are also in my collection. North Island only.
(3.)Flammulina (Therasia) celinde, Gray.
Distribution.—A fairly common shell in the northern parts of the North Island, but has not been found on it further south than the Urewera country. In the South Island it was found in Happy Valley, Canterbury, where also Phenacharopa novoseelandica, Pfr., occurs.
(4.) Flammulina (Therasia) decidua, Pfeiffer.
Distribution.—Found from Auckland to Otago. This is one of the very few New Zealand snails I have seen leaving its hiding-place after a warm rain and crawling up on shrubs with smooth bark, or devoid of it.
(5.)Flammulina (Suteria) ide, Gray.
Distribution.—Occurs over the entire North Island; in moist situations of the bush, and the northern part of the South Island. Its southernmost limit is, to my knowledge, near Lake Mahinapua, where it was found by Dr. A. Dendy.
(6.) Flammulina (s. str.) pilsbryi, Suter.
Distribution.—Like most minute forms, this species is widely distributed over New Zealand, and is found on both Islands. In the South Island I found it near the Mueller Glacier in some native bush
(7.) Laoma (s. str.) pcecilosticta, Pfeiffer.
Distribution.—This is a North Island shell, not uncommon in the bush near Auckland, but rare in the southern parts. It is one of the few specifically northern species that has reached the South Island as specimens were found in Marlborough.
(8.)Laoma (Phrixgnathus) glabriuscula, Pfeiffer.
Distribution,—Hitherto only known from Auckland Province, Hawke's Bay, and Taranaki, in the North Island, but, like the foregoing species, also from Marlborough.
(9.)Laoma (Phrixgnathus) phrynia, Hutton.
Distribution.—This rather rare species has been found from Whangarei to the Seventy-mile Bush, in the North Island; Marlborough, Nelson, Canterbury, and Hooker Valley, in the South Island; and a variety on Stewart Island.
(10.)Laoma (Phrixgnathus) allochroida, var.lateum bilicata, Suter.
Distribution.—A very minute form, living in mould in the bush, and hitherto only known from Auckland to the Fortymile Bush, in the North Island; also from Chicken Island.
(11.)Endodonta (Charopa) coma, Gray.
Distribution.—This is the only one of our land-shells that can be called common. It is found almost everywhere in the North Island, also on the Great Barrier Island. In the South Island it is, to my knowledge, not found south of the 44th degree of latitude; in the east, towards Banks Peninsula, it is replaced by Endodonta pseudocoma, Sut.
(12.) Endodonta (Charopa) colensol, Suter.
Distribution.—The type is from the Forty-mile Bush, and it has also been found near Auckland, and in Hawke's Bay, Waipawa, and Manawatu. Unknown from the South Island.
Thus it will be seen that most of the shells brought from Little Barrier Island are rather widely distributed in our colony.
With regard to the distribution of the genera, I may just mention that Rhenea, comprising small carnivorous snails, occurs as far as Queensland, New Caledonia, and one species (R. gradata, Gould) on the Tonga Islands. Flammulina is also found in Tasmania, Australia, Lord Howe Island, Norfolk Island, New Caledonia, and the Carolines; and nearly allied to it are Amphidoxa and Stephanoda, from South America, and Trachycystis, from South Africa. Once the anatomy of these genera is well known, they will most likely prove to form only one genus. Laoma, subgenus Phrixgnathus, is also known from Tasmania and southern Australia, but Laoma (restricted) is only found in New Zealand. To the same family, belongs the genus Puncium, which occurs in North America, Europe, part of Asia, and northern Africa. Endodonta, a Polynesian genus, occurs also in Tasmania, Australia, New Caledonia, the Philippine Islands, and over the Polynesian islands as far as the Hawaiian and Society Islands.