2. Genus Pitar Roemer.

Type: Venus tumens Gmelin.

Subgenus Hyphantosoma Dall.

Type: Cytherea carbasea Guppy.

Previously, Hyphantosoma was known only from the West Indian region where it has lived at least since the Oligocene (Woodring, 1925, p. 153, pl. 20, figs. 15–19). It is therefore surprising to find shells which must be referred here occurring in the Mid-Tertiary of New Zealand. The writer was dubious about this classification when he first made it several years ago; but the recent publication of Wood-ring's excellent figures of the genotype, and the acquisition, through the kind offices of Dr. K. van W. Palmer of Ithaca, N.Y., of specimens from the type locality, have placed the matter on a good foundation. The New Zealand shell is smaller than P. carbasea which comes from the Bowden formation (Miocene) of Jamaica; but it agrees closely in shape, lunule, escutcheon, sculpture and hinge. Minor differences exist; the right posterior cardinal is a shade broader; the anterior lateral pit is longer, and the sculpture is much weaker. These are only of specific significance.

Pitar (Hyphantosoma) sculpturatus (Marshall). (Figs. 74–76.)

1918. Macrocallista sculpturata Marshall, Trans. N.Z. Inst., vol. 50, p. 272, pl. 21, figs. 6, 6a.

Lunule large, lanceolate, bounded by a shallow groove. Sculpture of faint, zig-zag grooves on the anterior.

Hinge narrow, only slightly arched. Right valve with fairly broad, well-grooved posterior cardinal; median cardinal short, semi-circular in cross-section, not reaching top of hinge; anterior cardinal paired with median but placed higher up on hinge. Lower part of anterior cardinal projecting over deep groove leading from between two front cardinals to anterior lateral pit, which also is deep and has a weak lateral tooth above and one below. Left valve with posterior cardinal slightly separated from nymph; median cardinal bevelled, not grooved, joined above to lamellar anterior cardinal. Anterior lateral strong, slightly converging anteriorly with the lunular margin. Pallial sinus moderate, ascending, rounded at extremity. Valve-margins smooth.

Localities: Pakaurangi Point, Kaipara; bed 6A, Clifden, Southland.