i 7 4 DISCOVERY REPORTS 



lines. Umbo prominent, conical. Anterior end a trifle shorter and more narrowly 

 rounded than posterior. Hinge with two divergent cardinals in the left valve, the pos- 

 terior one the stronger and in the right valve two lamellae which interlock with the 

 cardinals. 



Length 4-55 mm.; height 3-3 mm.; thickness (one valve) 0-8 mm. (Holotype). 



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



The New Zealand species here described seems very similar to the New South Wales 

 genotype. The genus has not previously been found in New Zealand. 



Family THRACIIDAE 

 Genus Parvithracia, Finlay, 1926 

 Type (original designation) : Montacuta triquetra, Suter 

 Parvithracia cuneata, n.sp. (Plate XLVI, fig. 9). 



Shell small, solid, white, very inequilateral, wedge-shaped. Beaks low and rounded, 

 tips small, directed backwards, situated at about the posterior tenth of the length. 

 Anterior end greatly produced, gently descending and straight dorsally, narrowly 

 rounded medially, and broadly convex, almost straight, along the ventral margin. 

 Posterior end abruptly truncated, subangled at about half the height and again below 

 at the junction with the ventral margin. Hinge of right valve with a short very oblique 

 triangular cardinal, and a long groove running parallel to, and almost for the entire 

 length of, the anterior dorsal slope. Left valve not seen. Anterior muscle scar elongate- 

 ovate, posterior one circular. Pallial line interrupted by a broad fairly deep sinus. 



Length 5-2 mm.; height 3-7 mm.; thickness 1-2 mm. (Holotype). 



Habitat: Off Three Kings Islands, St. 934, 92 m. 



Although the extreme truncation of the posterior end in this species results in a shell 

 of very different outline from that of the genotype, the essential features of hinge and 

 pallial sinus are closely similar. 



Family CUSPIDARIIDAE 



Genus Austroneaera, n.gen. 



Type Austroneaera brevirostris, n.sp. 



This genus is proposed for an Austral group of trigonal-shaped Cuspidaria-like shells, 

 thin and smooth, with a very poorly developed rostrum. Hinge edentulous in the left 

 valve, an anterior and a posterior lateral in the right valve. There is a broadly rounded 

 pallial sinus. 



Austroneaera brevirostris, n.sp. (Plate XLVIII, fig. 11). 



Shell small, thin, ovate-trigonal, almost equivalve, white; rostrum short, truncated. 

 Anterior and posterior dorsal slopes fairly straight. Ventral margin gently convex, barely 

 incurved at the base of the broad truncated rostrum. Anterior end rather narrowly 



