299 



Ostrea hyotis, Linnfcus, 



1758. Mytilus hyotis, Linnaeus, Syst. Nat. ed. 10, p. 704. 



1870. Ostrea hyotis, Reeve, Couch. Icon. vol. xviii. pi. iv. fip^. 7. 



1886. Ostrt-a hyotis, Tate, Trans. Roy. Soc. South Aust. vol. viii. p. 96, 



pi. vi. fig. 0. 

 1889. Ostrea hyotis, Dennant, id. vol. xi. p. 49. 



Shell subquadrato, solid, typical examples having tube-shaped 

 spines upon large folds. As Professor Tate remarks, the fossil 

 specimens rarely exhibit tubular spines ; but the general contour 

 of the shell (which, however, is extremely variable in regard to 

 details) is that of the living 0. hyotis, and it has the characteristic 

 foliaceous scales of that species. 



Dimensions. — Height 112 mm. ; length 97 mm. 



Form, and Log. — Eocene: South Australia and Victoria. 



48803. Left valve showing traces of tubules; River Murray 

 clitis. Presented hy Commodore Goodenoitgh, R.N. 



L. 6581. Two left valves, with foliaceous plates, which are 

 not spiuose ; from Muddy Creek. Purchased. 



L. 10524. Two imperfect left valves, probably referable to 

 this species ; from XuUarbor Plains. M, Y. L. Brown Coll. 



L. 10525. Large left valve, not spinose, which is doubtfully 

 referred to 0. hyotis ; from Kiver Murray cliffs. 



Transferred from the Museum of Practical Geology. 



Ostrea sturtiana, Tate. 



1886. Ostrea sturtiana, Tate, Trans. Roy. Soc. South Aust. vol. viii. p. 97, 

 pi. vi. fig. 1. 



The only specimen in the Museum collection which approxi- 

 mates 0. sturtiana is so very much larger than that indicated by 

 Professor Tate, that the writer has some diffidence in assigning 

 it to that species. But in other respects it agrees so closely with 

 the diagno^^is given by the author, and the figure accompanyiijg 

 it, that for the present it may be regarded as a local variation, 

 characterized chiefly by the immense size of the shell. The 

 specimen in ([lU'stion is moderately excavated interiorly, whilst on 

 the exterior it is broadly and roughly ridged, and is scaly j the 



