SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 8g 



PLATE S, 



Prehistoric Fossils from Santa Rosa Island. California : 

 10. Saxidomus Nuttalli, Conrad. 

 11-12. Callista (Amiantis) Callosa, Conrad. 



13. Lucina Borealis, Linnaeus. 



14. Turritella Hoffmani, Cabb. Four specimens. 



15. Mactra (Ilarvella ) Elegans, Sowerby. No-w living at Pan- 



ama ovXj. 



16. Glycimeris Generosa, Could. Tavo specimens. 



17. Hinnites Crassa, Conrad. Three specimens. 

 18-2(». Ostrea Veatchii, Gal)b. 



21. Pecten pabloensis, Conrad. 



22-23 Liropecten Estrellanus, Conrad. (See foot note to 



Plate 6.) ■ 



24. Turbinella Caestus, P)r()(lei'ii). Found livini;- on ^lexiean 



coast. 



The Pliocene or Later Tertiary Period 



The Pliocene Period of the histoiy of California api)eals 

 more strongly to the inhabitants of the State than do all the 

 other geological periods "since the world was made." 



First— Because from its dei30sits the larger part of the im- 

 mense quantities of gold produced in this State have been 

 drawn for more than lifty years. 



Second — The Pliocene Gravel Beds are the burial places 

 of large numbers of the huge tertiary ]\Iammals represented by 

 the extinct Elephant and Mastodons. 



"We find that, in some unaccountable manner, our territory 

 was suddenly invaded by armies of huge tropical mammals, 

 whose fossil remains have been found in large numbers im- 

 bedded in the gold-bearing gravel of the flanks of the moun- 

 tains, the beds of the "dead rivers" of the Pliocene age, and 

 the later lacustrine beds and diluvial deposits of the entire 

 area of California. 



How came they here? Were they the progenitors of the 

 same genera now living in Asia and Africa, whose descendants 



