PATAGONIAN EXPEDITIONS ! PALAEONTOLOGY. 



EXPLANATION OF PLATE XVII. 



PAGE 

 OSTREA INGENS Zitt. 99 



Patagonian beds ; Shell Gap, lower horizon. 



Inner view of a lower valve of a very large individual, with very much 



elongate area ( phillippii Ortm.), corresponding closely to Zittel's 



type of O. ingens. 



Natural size. 



(VOL. iv) 



