24 Proceedings of the Royal Society of Victories. 



Limopsis morningtonensis, sp. nov. (Plate II., Fig. 6a). 



Descriptioji. — Shell roundly quadrate, depressed, slightly- 

 oblique, with a small, but prominent acute and incurved umbo. 

 Hinge line somewhat straight or very slightly curved, being 

 about half as long as the greatest antero-posterior diameter, with 

 a well-marked triangular pit immediately under the umbo, with 

 from 5 to 9 anterior teeth, and 4 to 7 posterior teeth of unequal 

 size, the medial ones of each series being strongest. Anteriorly 

 the shell is shorter than posteriorly, with the margin more 

 convexly rounded ; posteriorly there is a tendency to angulation 

 at the junction between the margin and the hinge, and again at 

 the junction with the ventral margin. Occasional specimens 

 show greater posterior obliquity, and a somewhat stronger keel 

 from the umbo to the posterior margin. Internally there is a 

 broad flattened margin, with the concavity finely radially striate. 

 Externally the surface is strongly concentrically ridged, the 

 ridges being of unequal strength, some fine, some bi'oad and 

 flattened ; a very close, regular and fine radial striation is 

 noticeable under a lens, though it is not, as a rule, visible to the 

 unaided eye, crossing the concentric ridges. 



Dimensions. — Type specimen, antei'o-posterior diameter, 

 14 mm. ; umbo-ventral diameter, 12 '5 mm. Other specimens 

 range for the above measurements respectively from 7 mm. by 

 6'5 mm., 10 mm. by 9 mm., 10 mm. by 10 mm., 1.3 mm. by 

 12 mm., up to 18 mm. by 15 mm. 



Localities. — Eocene clays near old Cement Works, Balcombe's 

 Bay, Mornington, also Grice's Creek. Eocene clays over 

 Polyzoal Rock, Filter Quarries, Batesford ; section near Griffin's 

 Farm, Moorabool River ; and Oi'phanage Hill, Geelong. Eocene, 

 Muddy Creek, Western District. Eocene clays of Gellibrand 

 River, coast section below Curdie's Steps (Type). Eocene, 

 Fishing Point, River Aire. 



Observations. — This shell seems sufficiently distinctive to 

 warrant specific designation, and should be easily separated from 

 our other species. It is possible that this is one of the forms 

 that has been confused with the European shell Limopsis aurita, 

 Brocchi, but there is very little difficulty in making out many 

 important distinctive features. Upon comparison with actual 



