Bartrum. — New Fossil Mollusca. 97 



Chione auriculata n. sp. (Plate VII, fig. 2.) 



Rounded-quadrate, small, rather compressed shell, almost equilateral ; 

 posterior end squarely truncated. Lunule large, lanceolate, very sharply 

 raised at dorsal margin into a prominent triangular ear-like portion ; 

 margins sharply incised. Beaks rather small, little raised, approximate ; 

 a distinct ridge from beak to lower angle of truncated posterior end of shell. 



Anterior dorsal margin forming triangular projection at lunule, the 

 anterior side of triangle shortly forming an angle with the rounded anterior 

 end. Posterior dorsal margin descends gently in convex curve to prominent 

 angle with straightly truncated posterior end. Broadly rounded basal 

 margin forms distinct angle at posterior end, and merges gradually into 

 rounded anterior end. 



Concentric ornamentation prominent ; growth-lines are densely crowded 

 and crossed by innumerable microscopic radiate lines. On lower half of 

 shell are strong, broad, rounded lamellae, distant and somewhat irregular, 

 6 almost complete lamellae visible. They broaden out at posterior ridge 

 of shell, and on dorsal portion beyond this are others nearer to the beak not 

 developed anteriorly beyond this ridge. The lamellae crowd on the lunule, 

 making it i:)laty. 



Hinge and other internal characters could not be observed. 



Length, 10-6 mm. ; height, 9 mm. ; diameter, 4-6 mm. 



Holotype in author's collection ; complete but for anterior half of left 

 valve. 



Localitv : Pakaurangi Point, Kaipara Harbour. Collected by Bartrum, 

 1916. 



Circulus cingulatus ii. sp. (Plate VII, figs. 3 and 4.) 



Very small, umbilicate. almost discoidal shell, coiled in a very flat spiral. 

 Whorls 3| or 4, very rapidly increasing, the protoconch smooth, the rest 

 sculptured by prominent spiral, angular, sharply elevated raised bands : 5 of 

 these are visible between the sutures on penultimate whorl, 15 on body- 

 whorl, regularly distributed, about 8 on basal portion, but absent from 

 umbilicus. Interspaces approximately ecjual in width to the ridges, striated 

 strongly by closely spaced transverse growth-lines, which alone ornament 

 umbilicus. 



Aperture somewhat incomplete, apparently circular, with a minute 

 posterior sinus. Outer lip partially incomplete in holotype, moderately 

 sharp, slightly crenate externally owing to spiral sculjjture. Inner lip fairly 

 solid, forming partial margin to the umbilicus ; this latter not widely open 

 and showing no coiling of whorls. 



Diameter, 4 mm. ; height, 1-9 mm. 



Holotype and two imperfect paratypes in author's collection. 



Localitv : Kawa Creek, south of Port Waikato. Collected by Bartrum, 

 1917. 



Remarks. — The late Mr. Suter remarked that this species comes nearest 

 to C. politus Sut., from which, however, it is quite distinct. 



Raeta tenuiplicata n. sp. (Plate VII, figs. 5 and 6.) 



Shell of moderate size, very thin, obovate in outline, anterior end 

 rounded, posterior produced and angled. Apparently agape anteriorly. 

 Beaks directed forwards, sharp, fairly swollen, on posterior half of shell, 

 approximate. From just below the beak a distinct wide shallow sinus passes 



4 — Trans. 



