Marwick.—Pliocene Mollusca from Hawke's Вау. 191 
Palaeontological Notes on some Pliocene Mollusca from Hawke's Bay. 
By J. Marwick, M.A., N.Z. Geological Survey. 
a E. permission of the Director of the N.Z. Geological Survey, before the Wellington 
cum Society, 9th rede 1922 ; received by Editor, 31st December, 1922 ; 
parately, 6th June, 1924.] 
Plates 16, 17. 
Tue following notes formed part of a paper on the geology of the 
Ngaruroro-Waipawa district, read before the тано Philosophical 
Society by Dr. Pa H. Uttley and the eal It is hoped that the main 
part of the paper will be published next yea 
All of the fossils mentioned below а. from the clays and sands 
known as the Petane clays, which underlie the Petane limestone and 
overlie the Te Aute limestone, and which are tipi exposed along 
be incorrect to use 
out by the late Mr. Suter, for many species regarded by him as Recent 
have been separated as distinct. The presence of the large Lutraria solida 
Recent forms, shows that the beds are older than the Castlecliffian 
(Marshall and Murdoch, 1920, p. 120), while many Upper Wanganuian 
species, such as Drillia buchanani (Hutton), Drillia wanganwiensis (Hutton), 
Bathytoma oT sd agg and Suter), Philobyra trigonopsis (Hutton), 
Struthiolaria frazeri Hutton, &c., forbid correlation with the Waipipian. 
Thus the Po Ms ы or Middle Wanganuian is indicated as the age of 
the Petane clays. 
Anomia undata Hutton. (Plate 16, figs. 9, 13.) 
1885. Anomia undata Hutton, Trans. n. — vol. 17, p. 324. Й 
1893. Anomia undata Hutton, Macleay Vol., p. 90, pl. 9, fig. 95. 
1915. Anomia undata Hutton : Suter, We Geol. Su urv. Pal. Bull. No. 3, p. 48 
This species was founded on “ undulations . . more or less 
parallel ” ая by the type and other specimens. It is well known 
that the animals of this genus reflect the sculpture of the shell to which 
they are attached, so the undulations are useless from a classificatory 
point of view. Those of the holotype are a copy of the coarse concentric 
sculpture of a pelecypod, perhaps Chione subsulcata Suter. Anomia u 
nevertheless, should be retained, for it has other quite distinctive features. 
Mr. W. R. B. Oliver, who has studied the Recent forms, found that 
A. huttoni could not be separated from A. trigonopsis; therefore it will be 
sufficient to differentiate undata from the latter species. The holotype is 
‘a young shell, and naturally does not show the distinguishing characters 
as clearly as the adult. That a very young A. undata agrees with the 
adult A. trigonopsis merely suggests that the former is an offshoot from 
the latter. In size A. undata far surpasses A. trigonopsis, the average adult 
has 
g 80-90 mm. in diameter, the shape where growth been free is 
circular to slightly oval, and the almost smooth surface is traversed by 
faint growth-lines and a few irregular concentric striae. The full-grown 
A. trigonopsis is generally under 50 mm. in diameter, and has often radial 
ribs, though this feature is not constant; the majority of large shells 
seen are inclined to be of irregular shape. The most reliable way to 
