301 



broadly excavated in the middle, whilst it is so disposed as to 

 bridge over a conical cavity ; muscle-marks elongate, excentric ; 

 external ornament consisting of irregular undulating ridges of 

 growth. 



The author compares it with 0. undata of the European Tertiary, 

 ■which it closely resembles. 



Dimensions. — Height 52 mm.; length 26 mm. 



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



L. 6582. Examples of both valves. Purchased. 



L. 9832. Several specimens of the adult, both valves. Pur chased. 



Ostrea nelsoniana(?), Zittel. 



1865. Ostrea nelsoiiiana, Zittel, Eeise der Xovara, Palaontologie, Bd. i. 



Abth. ii. p. 55, taf. xi. fig. 7. 

 1873. Ostrea nehoniana. Button, Cat. Tert. Moll. X.Z. p. 34. 



Shell elongate, ovate, solid. Left valve convex, irregular, 

 thickened, growth-lines laminated. Right valve flat, frequently 

 thick, growth-lines rugose. Umbones oblique, hinge broad, 

 furrowed ; pit triangular ; muscular impression large, lunate. 



Isone of the specimens in the Museum collection are exactly 

 like that figured by Professor Zittel, but they possibly come 

 within the permissible range of variation. They appear to be 

 more closely related to 0. nehoniana than to any other JS^ew 

 Zealand Ostrea. 



Dimensions. — Height 102 mm.; length 90 mm. 



Form, and Loc. — Miocene : New Zealand. 



L. 10517. Examples of both valves, of a rather elongate 

 variation ; from the upper end of Manawatu Gorge. 



Sir James Hector Coll. 



L. 10519. Complete specimen, left valve very convex, ovate ; 

 from Massacre Bay. 



Transferred from the Museum of Practical Geology. 



Ostrea -wrullerstorfi, Zittel. 



1865. Ostrea u-uUerslorf, Zittel, Reise dir Xovara, Palaontolog-ie, Bd. i. 



Abth. ii. p. 54, taf. xi. fig. 6. 

 1873. Ostrea wulUrstorJii, Hutton, Cat. Tert. Moll. X.Z. p. 34. 



Shell orbicular, flat, large. Left valve slightly convex, radially 



