936 PELECYPODA. [EulanieUtbranchm. 



2. Corneocyclas novae-zelandiae, Prime, 1862. Plate 54, figs. 9, a, 1>. 



Pisidium novce-zelandice, Prime, P.Z.S., 1862, 3 ; Ann. Lye. Nat. Hist. 

 New York, 1867, 91, fig. in text ; Button, M.N.Z.M., 155 ; T.N.Z.I., 

 xiv, 150, pi. 2, f. E, b. Corneocyclas novozeelandica, Prime : Suter, 

 T.N.Z.I., xxxvii, 244 ; f. 8 in text. 



Shell small, transverse, oval, oblique, very inequilateral, thin, 

 rather compressed. Beaks small and obtuse, finely concentrically 

 striated, the nepionic shell separated only by a fine ridge from the 

 adult shell. Anterior end produced, elongated, and rounded ; pos- 

 terior end shorter, broadly convex ; basal margin very lightly curved. 

 Epidermis thin, shining. Sculpture consisting of fine concentric lines, 

 which are crossed by more or less distinct, fine, microscopic radiate 

 striae. Colour yellowish-horn or greyish.' Interior of the same colour, 

 polished. Margins smooth, sharp. Hinge : Right valve with the 2 

 cardinals united, crescent-shaped ; left valve with 2 cardinals, the 

 posterior bifid, the anterior triangular. Ligament inset, very little of 

 it visible from the outside. 



Diameter Ant. -post.. 6 mm. ; dorso-ventral, 5 mm. : thickness. 

 3 mm. 



Type in the British Museum. 



Hab. North Island : Lake Takapiina ; Western Springs and 

 Onehunga Springs. Auckland ; Lake St. John ; near East Cape ; 

 Lake Waikare ; Wanganui ; Lake Taupo. South Island : Pelorus 

 River ; Nelson ; Rivers Avon and Heathcote ; creeks near Christ- 

 church ; Greymouth ; Lake Manapouri : Lake Wakatipu. in 10ft. to 

 30 ft. 



Sect. 2. PISIDIU.M. ('. Pfeitt'er, 1821. 



Type: Telliitn anniint. .Miiller. 



The 2 right cardinals not consolidated, the larger cardinal in each 

 valve typically bifid, the smaller one slender, entire ; the laterals 

 distant ; the ligament internal. 



3. Corneocyclas aucklandica, Suter, 1907. Plate 54, figs. 10, a-c. 



Corneocyclas aucklandica, Suter, P. Mai. S., vii, 1907, 211, j>l. 18, f. 1-1 f. 



Shell small, inequilateral, oval, and somewhat inflated. Beaks not 

 prominent, rounded, situate at the posterior third ; prodissoconch 

 smooth, convex, passing without strong demarcation into the adult 

 valve. Anterior end convex, dorsal margin nearly straight, slightly 

 descending ; posterior end much shorter, regularly rounded. Basal 

 margin broadly convex. Sculpture consisting of very fine concentric 

 stria?. Colour light yellow. Interior slightly whitish, smooth. Hinge : 

 Right valve with paired anterior and posterior laterals, 2 cardinals, the 

 anterior slender, broadly A-shaped, the posterior stouter, elongately 

 triangular, situate partly below and behind the anterior cardinal ; 

 left valve with single anterior and posterior laterals, 2 cardinals, one 

 in front of the other, the anterior tooth stouter, hook-shaped, and 



