330 Transactions. — Geology. 



Scalaria marginata. 



Shell large, elongated, imperforate. Whorls (?), flattened, distantly 

 longitudinally ribbed, 8 in a whorl, sub-equal, the interstices smooth or 

 very delicately spirally lined; the whorls sharply keeled at the base, the 

 keel shows in the spire whorls just above the suture ; the longitudinal ribs 

 end at the spiral keel ; base of the body whorl concave, smooth. Aper- 

 ture (?). 



Length, (?) ; breadth, *7 inch. 



Locality. Curiosity Shop. 



A fragment only of this very well-marked species is in the Canterbury 

 Museum. 



Trochus nodosus. 



Shell small, conical, imperforate, the spire acute. Whorls 6-7, flattened, 

 keeled, below the keel bent parallel to the axis ; keel placed a little above 

 the suture and with a single row of tubercles, about 9 on a whorl. Body 

 whorl bent vertically below the keel for a short distance and then flattened, 

 giving a double keel to the body whorl, the lower of which is smooth ; base 

 spirally striated ; apparently no umbilical callus. Aperture rhomboidal. 

 The whole surface of the shells appears to be finely cancellated with spiral 

 and longitudinal lines. 



Length, -54 inch ; breadth, -45 inch. 



Locality. White Eock Eiver. 



Corbula humerosa. 



Shell small ovato-trigonal, much inflated, smooth, with irregular growth 

 lines ; sub-equilateral, slightly produced and rounded posteriorly, not cari- 

 nated. 



Length, -25 inch ; height, -18 inch. 



Locality. White Eock Eiver. 



Corbula pumila. 



Shell small, ovate, concentrically sulcated ; sub- equilateral, slightly 

 produced and truncated posteriorly ; slightly angled. 



Length, -3 inch ; height, -22 inch. 



Locality. White Eock Eiver. 



Differs from C. erythrodon in being shorter and less angled behind. 

 From G. sulcata it differs in being larger, more compressed, and in the sulci 

 being smaller and more numerous. 



Pholadomya neozelanica. 



Shell oblong, very inequilateral, moderately ventricose, the posterior end 

 compressed. Concentrically ridged, about 12 to an inch; the ridges rounded, 

 broader than the grooves. Central portion radiately ribbed, ribs moniliform, 

 not so strong as the concentric ornamentation, about 20 in number, the two 



