i68 



DISCOVERY REPORTS 



Family DIMYIDAE 



Genus Dimya, Rouault, 1850 



Type : Dimya deshayesiana, Rouault 



Dimya maoria, n.sp. (Plate XLV, fig. 2). 



Shell irregularly ovate, slightly oblique, higher than long. Left valve free, undulating 

 exteriorly, somewhat arched over the upper portion but becoming actually concave 

 before the basal margin is reached. Right valve with a large area of attachment and 

 rather steep short sides. Surface of valves irregularly malleated, but with no true 

 sculpture. Umbo small, projecting, about central, with small deep triangular chondro- 

 phore immediately below it. Hinge line straight and rather long. Interior with a 

 deeply incised simple pallial line, outside of which is a broad smooth slightly convex 

 marginal shelf, bearing numerous faint radial riblets, about thirty in the holotype 

 (obscure over the basal and posterior margins). Muscle scars typical, a small oval 

 anterior one high up and a double (figure 8) posterior one situated at about half the 



height of shell. 



Length 6- 1 mm. ; height 77 mm. ; maximum thickness 1-5 mm. (Holotype, a left valve). 



Habitat: Off Three Kings Islands, St. 933, 260 m. 



This species is characterized by its malleated surface and complete absence of radial 

 sculpture. The genus is new to the New Zealand fauna but occurs in both Recent and 

 Tertiary deposits in New South Wales and Victoria respectively. 



Family LIMIDAE 



Genus Limatula, Searles Wood 1839 



Type : Lima subauriculata, Montagu 



Limatula aupouria, n.sp. (Plate XLVII, fig. 4). 



Shell very small, elongate-ovate, slightly oblique, equivalve and almost equilateral. 

 Beaks bluntly rounded, tip smooth, followed by a brief development of very fine and 

 closely spaced concentric lirae. Ears small, almost equal; the anterior one slightly 

 higher than the posterior. Sculpture consisting of a few strong rounded radial ribs, 

 which are imbricated by sharp concentric lamellae. The radials number seventeen; 

 those at the extremities being indistinct. Also, the radials fade out above at the com- 

 mencement of the post-embryonic concentric lirations. The later concentric sculpture 

 begins to develop at about two-thirds the height of the shell, after which the riblets 

 become stronger and more lamellose as the margin is approached. The radials are less 

 than half their own width apart and the concentric lamellae about twelve per millimetre. 

 Colour dull white. Hinge plain, resiliary pit broadly triangular. Interior radially in- 

 dented, corresponding to the external ribbing. 



