PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



EXPLANATION OF PLATE XV. 



PAGE 

 OSTREA INGENS Zitt. ........... 99 



Patagonian beds ; mouth of the Santa Cruz River. 



Very large individual, side view, natural size (transitional form between var. 

 hatcheri and phillippii Ortm. 



(VOL. iv) 



