330 



Crenella globularis, Tate. 



1886. Crenella globularis, Tate, Trans. Eoy. Soc. South Aust. vol. viii. 



p. 126, pi. X. figs. Za-b. 

 1889. Crenella globularis, Dennant, id. vol. xi. p. 49. 

 1893. Crenella globularis, Tate and Dennant, id. vol. xvii. pt. 1, p. 224. 



Shell subglobose, nacreous within, equivalve, inflated ; inequi- 

 lateral, the umbones being placed anteriorly, they are obtuse and 

 incurved ; ligamental groove internal, extending posteriorly ; hinge- 

 line minutely transversely denticulated ; a denticle terminates 

 the groove under the umbo ; margin of the valves faintly crenu- 

 lated ; the surface is regularly cancellated. 



It is a close ally of C. elegaiis, Deshayes, of the Paris Basin. 



Dimensions. — Height 5 mm. ; length 3-5 mm. 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



L. 9874. Several examples of both valves. Purchased. 



Crenella elongata, Hutton. 



1873. Crenella elongata, Hutton, Cat. Tert. MoU. N.Z. p. 25. 



Dimensions. — Length 14 mm.; breadth 8 mm. 

 Form, and Loc. — Eocene : Trelissick, New Zealand. 



L. 10486. Internal cast of the left valve. 



Sir James Sector Coll. 



Family ARCID^. 



Genus ARCA, Linnaeus. 



[Syst. Nat. ed. 10, 1758, p. 693.] 



Shell commonly equivalve, subrhomboidal, ventricose, costulate 

 or cancellate ; borders of the valves either smooth or dentate ; 

 hinge straight, horizontal, furnished with very numerous, short 

 teeth ; umbones prominent, curved inwards, separated from each 

 other by a more or less broad area, which carries several liga- 

 mental striae or well-marked, narrow, linear grooves commonly 

 V-shaped ; impressions of the adductor muscles of the valves 



