78 Transactions, 



short, excavated below the beak, thence almost straight and slightly declining, 

 the end obliquely truncated, basal margin lightly curved, ascending a little 

 more rapidly to the anterior end ; the posterior area is defined by a broad 

 subangular ridge which descends from near the beak to the lower margin 

 of the truncation, a smaller ridge similarly proceeding unites with its dorsal 

 margin. Sculpture consists of fine growth-lines, irregular in places, and 

 more pronounced on the posterior area ; there does not appear to be any 

 radial sculpture. Hinge without teeth, but with a strong inward-projecting 

 lithodesma ; the pallial sinus and adductor impressions obscure, the 

 posterior adductor apparently large and near to the end. 



Length, 78 mm. ; height, 49 mm. ; diameter of a single valve, 14 mm. 

 Another valve : length, 68 mm. ; height, 44 mm. 



Type to be presented to the Wanganui Museum. 



Locality : On the coast about three miles north of the Waipipi Stream, 

 in brown sand and blue sandy clay. 



The material consists of two right valves and one left, the latter rather 

 fragmentary. In size it may be compared with Thracea sp. H. Woods, 

 N.Z. Geol. Sur. Bull. No. 4, p. 34, pi. 19, figs. 4a, 46. It shows even greater 

 convexity than that species, and the beak is distinctly more posterior. 



Miltha neozelanica n. sp. (Plate XVI, figs. 1, 2, and Plate XVII, fig. 1.) 



Shell large, ovately subrotund, compressed, left valve distinctly more 

 compressed than the right ; beaks small, curved forward, and nearer to the 

 anterior end ; immediately in front of the beak is a small triangular area 

 of the margin sharply inflexed to almost half the depth of the hinge-plate ; 

 the anterior dorsal area narrow and inconspicuous, the margin convex, 

 declining, and forming a small distinct angle at the end, from this is a wide 

 uniform curve continued around the ventral margin and terminating in a 

 more pronounced angle at the posterior end ; the posterior dorsal margin 

 convex and regularly declining. On the posterior dorsal area of each valve 

 one or two feeble corrugations following the curve of the margin. Sculpture 

 consists of fine concentric threadlets, somewhat irregular towards the ventral 

 margin, and rather more sharply raised on the posterior dorsal area ; 

 radiate striation is very obscure, indications of it in places only. The 

 hinge-plate wide with two cardinals in each valve, the anterior small, 

 separated by a narrow triangular pit ; laterals consisting of a simple ridge 

 on each side, the posterior almost obsolete ; ligament and resilium deeply 

 inset. Adductors, the posterior small ovate, the anterior large and much 

 elongated, the lower end almost in a line vertical to the beak ; pallial line 

 impressed and distant from the margin, the latter smooth. The disc is 

 more or less punctate and with small raised processes indicating attachment 

 of the mantle ; all valves have a rather broad oblique sulcus on the 

 middle area. 



Height, 94 mm. ; length, 91 mm. ; thickness of united valves, 32 mm. 

 A right valve : height. 64 mm. ; length, 68 mm. 



Type to be presented to the Wanganui Museum. 



Locality : On the coast about three miles north of the Waipipi Stream, 

 in brown sands and in blue sandy clay ; also in the sea-cliff near to the 

 Hawera County metal-pit, Whakina. 



In the list of fossils occurring in the Waipipi beds this species is recorded 

 as Dosinia magna Hutton (Trans. N.Z. Inst., vol. 52, p. 124, 1920). In 

 large specimens the anterior and posterior angles are more or less obscure . 



