Ps(tinniobiti.\ PELECYPODA. 1 003 



prominent on the posterior dorsal area, and fine rather distant radiate 

 strise. Epidermis thin, polished. Colour pinkish-white with variable 

 concentric bands of purple, and distant very unequal radial rays of 

 white, sometimes inconspicuous. Interior reddish -purple, whitish on 

 the margins and hinge, smooth, shining. Margins smooth. Hinge 

 narrow, right valve with 2 bifid cardinals ; left valve with 1 bifid and 

 a rudimentary anterior cardinal. Ligament short, external, much 

 raised. Adductor-scars subequal, very superficial. Pallial sinus long 

 and broad, coalescent below with the pallia! line, narrowly rounded in 

 front. 



Length, 54 mm. ; height, 28 mm. ; diameter, 11 mm. 



Type in the British Museum. 



//#fr. North and South Islands, and Chatham Islands ; in sand 

 and mud in the laminarian and coralline zone. 



Fossil. Miocene and Pliocene. 



Subgen. 2. GOBR^US, Leach, 1852. 



Gobrceus, Leach, Moll. Gt. Brit,, 1852, 265. Type : G. variabilis, Leach = 

 Solen vespertinus, Gmelin. 



Shell inflated, more or less truncate behind ; concentrically striate 

 or nearly smooth, often with fine radial striae, especially evident on 

 the posterior dorsal region ; teeth variable, not more than 3 in the 

 right and 2 in the left valve ; sinus rounded in front, rarely shorter 

 than the vertical of the beaks, and often more or less detached from 

 the pallial line. 



This group has no circumscription of the dorsal areas, and differs 

 from Psammobia most obviously in its blunt and inflated form, with 

 a distinct posterior gape. (Dall.) 



KEY TO SPECIES. 



A. Shell moderately large and very solid, with fine concentric striae 



which are not much raised . . . . . . . . Stung eri. 



B. Shell rather small and thin, with sharply raised concentric striae 



which are lamellate and wavy oil the posterior dorsal end . . -elandica. 



"2. Psammobia Stangeri, Gray, 1843. Plate 61, figs. 9. n. 



Psammobia Stangeri, Gray, Dieff. N.Z., 253 ; C.M.M., Co ; Conch. Icon., x, 

 1856, f. 12 ; Grit. List, 42 ; M.N.Z.M., 141 ; Hutton, J. de Conch., xxvi, 

 46 ; P.L.S. N.S.W., ix, 519. 



Shell moderately large, oblong, solid, rather ventricose, concen- 

 trically striated, purplish-white with radial rays of darker. Beaks 

 contiguous, but little raised, situate a little in front of the middle, 

 blunt and incurved. Anterior end a little shorter, convex, the dorsal 

 margin nearly straight, very slowly descending ; posterior 1 end obliquely 

 truncated, narrowly rounded below, the dorsal margin straight, hori- 

 zontal, ventral margin very little convex. The posterior dorsal area 

 very faintly marked by a blunt ridge descending from the umbones. 



