Genus PARYPHANTA Albers, 1850.
Sub-genus POWELLIPHANTA nov.
Shell generally, similar to Paryphanta Albers, but with the last whorl pulled in closer to the preceding whorl, and with a colour pattern of concentric or radially arranged bands, usually of
alternating and contrasting colours. More important is the paucity of lime compared with conchin in the shell.
Egg always with cuticle, pale buff when laid.
Distribution: North Island of New Zealand, in and south of the Ruahine Range (possibly once as far north as East Cape) and South Island.
Type: Helix hochstetteri Pfeiffer, Mal. Bl., viii, 146, 1862 (see PI. 6, Figs. 5–8).
Powelliphanta will include all New Zealand species previously included in Paryphanta except the type of that genus, P. busbyi (Gray, 1840) which is confined to the North Auckland Peninsula.
(For list, see Powell, 1938, pp. 140, 141.)
The sub-genus is named in recognition of the great service rendered to the study of the family by Mr A. W. B. Powell.
P. busbyi (PI. 5) has a very thick coating of conchin, as well as an inner limy shell, and specimens are not infrequently found in North Auckland Pleistocene dune deposits which have weathered down to a strong, limy shell even when all the conchin has gone. All other New Zealand Paryphantas have a flexible shell composed chiefly of conchin with a much reduced limy layer, so that they generally collapse soon after death. Powelliphanta is known in a sub-fossil condition only in limestone caves where replacement of conchin by lime has apparently occurred. Empty, “dead” shells of some species of Powelliphanta, which are mostly conchin with practically no inner limy shell, such as gagei, fletcheri, rossiana and spedeni, are sometimes so collapsed and distorted when found that they appear worthless as specimens. They can usually be restored, however, by soaking in very hot water, but on no account must they be lifted out until the water is absolutely cold. In most cases, if this is done, it will be found that the shape has been brought back without any alteration in colour. On no account must any of the other coloured species be treated in this way, otherwise the colour will be spoilt.