Dosinia.] PELECYPODA. 979 



forwards, approximate. Posterior end regularly curved, sometimes a 

 little straightened, the dorsal margin arcuate, high, very slowly de- 

 scending ; anterior end convex, the dorsal margin short, excavated 

 in front of the beaks ; ventral margin semicircular. Lunule short, 

 cordate, lamellate, deeply impressed. Escutcheon long, narrow, and 

 deep, with prominent keels. Sculpture consisting of concentric, ele- 

 vated, rather distant, sharp ribs, which are getting convergent and 

 lamellate at the anterior, and much more so at the posterior dorsal 

 end ; faint radiate striation is present. Colour light-yellowish or reddish- 

 brown. Interior white, porcellanous, dull. Margins smooth, blunt. 

 Hinge-plate broad and strong, arcuate ; right valve with 4 cardinals, 

 the anterior small, the second strong, subvertical. triangular, the third 

 very oblique and long, and the fourth forming a fine and low lamella, 

 subparallel to the third tooth, obsolete in adult shells ; the 2 anterior 

 lateral teeth are small, below the anterior cardinal, and much cor- 

 rugated ; left valve with 3 cardinals, the anterior subvertical, long, 

 and narrow ; the second very stout, oblique ; and the third subparallel 

 to the latter, long, low ; the anterior lateral tooth is large, triangular, 

 close in front of the cardinal, much corrugated. Ligament long and 

 strong, extending from the umbones to within a short distance of the 

 end of the hinge-plate ; the resilium much developed. Adductor-scars 

 almost equal, deep, pyriforni. Pallial line very distinct and distant 

 from the margin ; the parallel sinus horizontal, short, and triangular, 

 the angle pointing below the anterior adductor-scar. 



Length, 49mm.; height, 46-5 mm. ; diameter, 18mm. (type). 

 Length, 72 mm. ; height, 71 mm. ; diameter, 32 mm. (large specimen). 



Type of A. australis, Gray, in the British Museum. 



Hob. North and South Islands, but not found south of Oamaru ; 

 Kermadec Islands (Captain Bollons). 



Fossil in the Pliocene. 



4. Dosinia subrosea, Gray, 1835. Plate 60, figs. 10, a. 



Arthemis subrosea, Gray, Yate N.Z., 1835, 309. Artemis subrosea, Gray 

 Dieff. N.Z., 249 ; Conch. Icon., vi, 1850, f. 19 ; Thes. Conch., ii, 1852. 

 669, pi. 143, f. 61 ; Crit. List, 44 ; Hutton, J. de Conch., xxvi, 48 ; 

 M.N.Z.M., 150. Dosinia subrosea, Gray : Homer, Nov. Conch., Dosinia, 

 1862, 68, pi. 13, f. 3 ; C.M.M., 72; Ere'b. & Ter., fi, pi. 3, f. 2 ; Hutton. 

 P.L.S. N.S.W., ix, 523 ; Index, 89. 



Shell moderately large, orbicularly ovate, inequilateral, fairly solid, 

 closely concentrically striated, valves rather convex, light pinkish - 

 brown. Beaks tumid, but little prominent, approximate, situate at 

 about the anterior two-fifths of length, sharply pointed, and directed 

 forwards. Anterior end broadly convex, the dorsal margin narrowly 

 and deeply excavated in front of the beaks ; posterior end straightened 

 at the middle, narrowly rounded towards the long, curved, and rather 

 slowly descending dorsal margin ; basal margin semicircular. Lunuk 

 short, cordate, deep, striated. Escutcheon narrowly lanceolate, deep 

 and narrow, prominently keeled. Sculpture consisting of close con- 



