296 Transactions. 



width as the ribs ; the whole surface ornamented with distant concentric 

 striae, imbricating the ribs. Left valve with subequal triangular ears, the 

 anterior ear with fine radial riblets crossed by distant laminar concentric 

 striae ; the posterior ear without distinct radial riblets, but rather distant 

 lamellar concentric striation ; disc with 11 subequidistant, high, rounded 

 radial ribs, the 3 posterior interstices with a low, broadly rounded rib in the 

 centre, bringing the total number of ribs up to 14 ; the whole surface with 

 fine, dense concentric striation. Margins smooth inside. Hinge-plate 

 solid, with a large, oblique, triangular resilifer, directed forwards. Adductor- 

 scar very large, rounded, slightly longer than high, vertically striated, 

 situation central or slightly posterior. 



Right valve: Height, 115mm.; length, 120mm.; diameter, 20mm. 

 (holotype). 



Left valve : Height, 107 mm. ; length, 108 mm. ; diameter, 25 mm. 

 (holotype). 



Holotypes in the collection of Dr. P. Marshall, Otago University, Dimedin. 



Locality. — Muddy Terrace, Waikaia (Dr. P. Marshall). Miocene. 



Remarks. — The upper part of a right valve from limestone on coast, ten 

 miles north of Eaglan (loc. 97), is in the Museum of the Geological Survey, 

 Wellington. This specimen has the anterior ear in perfect condition. 



Venericardia ponderosa sp. nov. Plate XII, fig. 1. 



Shell large and solid, rounded trigonal, inequilateral, the umbo near the 

 anterior end, with flatly rounded, nearly smooth radial ribs, the anterior 

 ones narrow and scaly, the posterior ribs inconspicuous, concentric striation 

 prevailing. Beak very near the anterior end, large, inflated, incurved, 

 prosogyrate. Anterior end very short, flatly convex, the margin rounded, 

 dorsally deeply excavated. Posterior end very long, moderately ventri- 

 cose, broadly rounded, the dorsal margin almost straight and long, slowly 

 descending ; basal margin broadly convex. Lunide small, cordate. 

 Escutcheon linear. Sculpture consisting of 25 conspicuous radial ribs, to 

 which about 5 inconspicuous posterior ribs have to be added ; the 6 anterior 

 ribs are narrow, rounded, scaly, the interstices broader than the ribs ; the 

 median ribs of the valve are broadly convex, stout, crossed by fine concentric 

 growth-lines, the interstices very narrow ; on the posterior end of the valve 

 the ribs are flattish, low, inconspicuous, lamellar concentric striation pre- 

 dominating. Margins distinctly plicated, thick. Hinge-plate broad and 

 heavy, left valve with 2 cardinal teeth, the anterior tooth short and thick, 

 blvmt, oblique, the posterior tooth long, nearly horizontal, arched, finely 

 transversely striated. Ligament rather long, external. Adductor-scars un- 

 equal, large, deep, the anterior elongately oval, the posterior roimded 

 subtrigonal. 



Left valve : Height, 80 mm. ; length, 100 mm. ; diameter, 38 mm. 

 (holotype). 



Holotype in the collection of Dr. P. Marshall, Otago University, Dunedin. 



Locality. — Muddy Terrace, Waikaia (Dr. P. Marshall). Miocene. 



Chione (Lirophora) speighti sp. nov. Plate XIV, figs. 1 and 2. 



Shell rather large, ovate, subpentagonal, flatly convex, inequilateral, 

 with submedian and posterior angle, with distant concentric lamellae, and 

 a submedian and posterior ridge, angulating the concentric lamellae. Beaks 

 approximate, very little raised, incurved and directed forwards, with an 



