Comprehensive DescriptionRead full entry
“Limatula maoria n. sp. (Figs. 104-106).
Shell close to L. strangei Sow., but differing in outline, being less slender, more oblique, and more evenly rounded basally. Sides not nicked in so much below auricles, so that these are less prominent; dorsal margin straighter. Radial ribs lower and blunter, closer and more numerous, 25 as against 19 in Australian shells. Internally, a median sulcus is absent or very feeble in strangei, but is distinct in the new species at all stages of growth.
Height, 33 mm.; diameter, 20.5 mm.
Locality,—Castlecliff beds (Upper Pliocene), type (fig. 106); off Otago Heads in 60 fathoms, figd. paratypes (Figs. 104, 105), not uncommon throughout New Zealand in water of moderate depth.
The median sulcus has been responsible for the identification of juveniles of this species as L. suteri Dall by both Suter and later workers; but the latter species has about 16 ribs on each valve, the termination of sculpture on each side is less well defined, and the sulcus is external, so that the interior shows a strong medial rib with another strong one on each side; maoria shows a medial groove with a strong rib on each side. As ancestral to this species in New Zealand may be named Limatula trulla Marwick (Trans. N.Z. Inst., vol. 56, p. 311, 1926) and Lima (Limatula) huttoni Woods (1917, p. 26), a Cretaceous form which has been renamed L. woodsi by Suter on account of preoccupation; see note elsewhere in this volume. An Australian form ancestral to strangei Sow., L. jeffreysiana Tate has rightly been rejected by Marwick from the New Zealand Tertiary fauna Rep. Austr. Assoc. Adv. Sci., vol. 16, p. 323, 1924); the differential features between maoria and strangei seem to be continued throughout the lineages.”
(Finlay, 1927: 454)