24 Studies in Gkology, No. 3 



knowledge it appears to be later Burdigalien in age. Such 

 a difference between the Upper and Lower Zorritos forma- 

 tions is not irrational to suppose when we consider that the 

 A'ariegated formation, with its continental beds, may contain 

 a hiatus of considerable magnitude. 



As might be expected, the fauna as a whole has its nearest 

 relatives in the general region between Panama and Florida, 

 The alternative anticipation would be to look for affinities in 

 the Tertiary of Chile, Patagonia, and New Zealand, and 

 although in rare cases such occur, they are not suggestive of 

 any well-defined connection between the faunas of the two 

 regions. Grzybovvski noted the presence of affinities with 

 the Xavidad and Coquimbo beds of Chile, five of the sixteen 

 species in his Heath (=Variegated) faunule being identical 

 with or closely related to Chilean species. These five species 

 are all in his list from the locality north of Caleta Grau, 

 near Alalpaso, at which he was unquestionably dealing with 

 the Variegated formation. No such species has appeared 

 in the Hopkins collection, and very few which show any 

 affinity to Chilean species. Grzybowski noted no Chilean 

 element in his Zorritos fauna, which is equivalent indiscrim- 

 inately to the present Upper and Lower Zorritos. He did, 

 hov/ever, note a Chilean element in his Payta fauna. 



It is probable that at least during the periods of the Upper 

 and Lower Zorritos formations connection with the south- 

 ern coast was cut off. A point of land similar to that about 

 Point Aguja and Gabo Blanco, which now diverts the colder 

 Humboldt current seaward, and marks the northern limit of 

 the Peruvian Province, probably existed farther to the 

 south during part of Miocene time, giving rise to conditions 

 similar to those now existing, but with the southern limit 

 of the purely tropical littoral, corresponding to the present 

 Panamic Province, farther south. The location of such a 

 point at the various stages of the Tertiary will be known 

 when the coastal geology and paleontology have been 

 studied in greater detail and over the entire area. 



