159 



f ourtti of tlie entire length o£ the shell from the anterior end. 

 The lunule is narrow-lanceolate, ill-defined, faintly circum- 

 scribed, and slenderly striated. The exterior of the valves is 

 somewhat shining, coarsely concentrically striated, and bears 

 a few remote concentric ribs, which are raised into scale-like 

 lamellae at the front margin and on the posterior slope, appear- 

 ing on the latter in two rows, corresponding with the two ob - 

 scure ridges, which proceed from the umbo to the angles of the 

 posterior truncation. Ventral margin finely crenulated. 4 : 



Dimensions. — Antero-posterior diameter, 39 ; umbo-ventral 

 diameter, 30; sectional diameter of both valves, 21 milli- 

 metres. 



Locality. — Very common in the younger beds at Muddy 

 Creek, Hamilton. 



This species closely resembles the living Callista Victories, 

 Tenison- Woods (=Chione rutila, Hanley), from which it differs 

 by being proportionately longer, by the more acuminate and 

 biangulated posterior extremity, by the flatter posterior slope, 

 which is usually ornamented with two rows of elevated scales. 



Cytherea Murrayana, spec. nov. Plate xiv., fig. 18. 



Perhaps only an extreme form of C. paucirugata, nearly as 

 "broad as long ; more widely truncated, and not at all acumi- 

 nated posteriorly ; the scale-like lainellse small and developed 

 on the anterior and post-dorsal margins only ; the posterior 

 slope is more angulated, and the lunule is much wider and 

 deeper. Faint and distant radial threads are here and there 

 visible on the surface. 



Dimensions. — Antero-posterior diameter, 32 ; umbo-ventral 

 diameter, 29 millimetres. 



Locality. — Oyster beds of the Eiver Murray Cliffs at Xor'- 

 West Bend. 



Cytherea tenuis, spec. nov. Plate xiv., fig. 16. 



Transversely-oval, thin, moderately convex, inequilateral, a 

 little narrower in front than behind, where it is somewhat 

 truncated. The umbo is rather small incurved, situated at 

 about one-fourth of the whole length from the front. The post- 

 dorsal margin is elongate, nearly straight, the anterior being 

 much shorter, more descending, and slightly curved ; the ven- 

 tral outline is gently arcuate, ascending more in front than be- 

 hind. The lunule is broadly lanceolate, shallow, striated, and 

 circumscribed by an impressed line. The exterior surface is 

 shining, very finely concentrically striated. 



The margin of the valves is plain. 



The pallial sinus is large, broad, deep, obliquely ascending, 

 extending to the centre of the valve, abruptly rounded at the 

 end. 



