Older Tertiary of Victoria. 99> 



Umbo acute, incurved a little to the front of the medial line, 

 with a very small, deep, but relatively broad, cordate lunule, and 

 further down two faint curved o;rooves radiating from the umbo to- 

 the anterior margin ; shell much depressed anterior to the lunule 

 and inclined to shouldering or angulation at the downward curve of 

 the anterior margin ; dorsal margin straight, downwardly inclined, 

 and somewhat angulate with the posterior margia ; a change in 

 the convex curvature of the ventral margin can be noted from 

 that of the anterior and posterior margins, and this, together 

 with the shouldering, gives rise to the quadrate appearance of 

 the shell. 



Surface sculptured by fine close concentric ridges which tend 

 to become lamellose anteriorly and posteriorly, numbering about 

 20 in 5 millimetres from the ventral margin in average sized' 

 specimens, but running closer and finer towards the umbo. No- 

 radial sculpture present externally, but internally there is a faint 

 radial striation terminating at the margin in faint crenulations. 



Diinensio7is. — Type specimen, antero-posterior diameter, 13 

 mm.; umbo-ventral diameter, 12 mm.; others range from 12 

 mm. by 11 mm., 12-.5 mm. by 12 mm. to 14-5 mm. by 14-5 mm.;, 

 thickness through both valves of specimen 12-.5 by 12 is 6 mm. 



Localities. — Cxrey clays of Grice's Creek or Gunyoung Creek,. 

 Mornington. Balcomlnan, — ^Eocene. I>ower beds of the Spring, 

 Creek series or Bird Rock Blufi', near Geelong. Jan Jukian, — 

 Eocene. 



Observations. — Tliis species is apparently most closely related 

 to L. leucomomorpha, Tate, but is more depressed, with the- 

 umbos more anterior, more deeply excavated anterior to the- 

 umbos, and differently sculptured. 



Chione etheridgei, sp. nov. (Plate XXL, Fig. 1). 



Description. — Shell large, transversely oval, tiiick, and only 

 moderately convex; greatest convexity near- the umbo, and with 

 a marked flattening towards the ventral margin; deeply concavely 

 excavated antei'ior to the umbo. 



Umlio very prominent, incurved anteriorly, and .situated about 

 one-third the length of tlie shell from the anterior margin. 

 Lunule distinct, elongate cordate, and slightly raised to a medial) 

 ridge along the junction of the valves. Dor.sally immediately 



