5Qi REPORT — 18C3. 



p. ge. Plate. rj>. V, . , 



TO. II. 4. il-iy« MmiUreyana, Conr., p. 313. [Figure resembles Fenploma 



ari/eiitaria.'] Monterey Co. 

 „ „ 5. ?J\ji/a siihsinuata, Com: [Conrp.A/ocomamymVtate.]_ Monterey Co. 



,, „ 6. Arcopcif/ia medialis, Conr., p. 314. Like A. hipjicata, Conr., of 



the Maryland Miocene. [Closely resembles Latricola alta, Conr.] 



Monterey Co. 

 „ „ 7. Tapes liideaium, Conr., p. 314. California. 



„ „ 8. Area canalis, Cor.r., p. 314. Santa Barbara. 



„ „ 9. Area triUnmta, Conr., p. 314. Sai^ Barbara. 



„ „ 10. ^/-ca eofl/zcs/a, Conr., p. 314. California. 



71. III. 11. AxirKeaBarharensis, Com. [Closely resembles Peci. J«fe)'»neA'«s.J 

 „ „ 12. Mtdinia densata, Conr., p. 313. ? Santa Barbara and sbores of 



Pablo Bay. 

 „ Dosinia Imu/vla, Conr., p. 815. Monterey. 



„ „ 13. Dosinia alia, Conr., p. 315. Monterey. 



„ „ 14. Peeten Pabloensis, Conr. San Pablo Bay. 



„ „ 15. Pallium Ustrellanum, Conr., p. 313. Estrella Valley. 



„ „ 16. Janira lella, Conr,, p. 312. Santa Barbara. 



'^^' ^y' 17' I ^^^^'"'^ Titan, Conr., Phil. Proc. 1856. San Luis Obispo. 



73. V. 25. Pandora hilirata, Conr., p. 267. [Closely resembles Kennerlia 



biearinata.'] Santa Barbara. 

 „ „ 24. Cardita oceidentalis, Com. ,1855, 'p.267. [? = C. ventricosa, Gli.l 



Santa Barbara. 

 „ „ 23. Diadora erue^uliformis, Conr., 1855, p. 267. \^ = Puncturella 



Citeullata, Grid.] Santa Barbara. 



Fossils of Oatwn, Isthmus of Darien. 



72. V. 22. Malea ringens, Swains. Gatun. 

 „ „ 19. Turritella altilira, Conr. Gatun. 



^^ „ 20. Turritella Oatunensis, Conr. Gatun. 



„ „ 20. Triton, sp. ind. Gatun. 



„ „ 21. ? Cytherea Dariena, Conr. [The fig-ure does not appear conspe- 



cific with that in the Blake collection, no. 50.] Galun. 



The northern fossils are supposed by Mr. Conrad to be of the Miocene period, 

 and not to be referable to existing species. Those from Sta. Barbara, however, 

 are clearly of a very recent age, and probably belong to the beds searched by 

 Col. Jewett. But by far the most interesting result of Dr. Newberry's ex- 

 plorations was the discovery of the very typical Pacific shell, Malea ringens, 

 in the Tertiary strata on the Atlantic slope of the Isthmus of Darien, not 

 many miles from the Caribbean Sea. The characters of this sheU being such 

 as to be easily recognized, and not even the genus appearing in the Atlantic, 

 it is fair to conclude that it had migrated from its head waters in the Pacifi.o 

 during a period when the oceans were connected. We have a right, there- 

 fore, to infer that during the lifetime of existing species there was a period 

 when the present separation between the two oceans did not exist. We 

 may conclude that species as old in creation as Malea ringens may be found 

 still living in each ocean ; and there is, therefore, no necessity for creating 

 " representative species," simply because, according to the present configu- 

 ration of our oceans, we do not see how the molluscs could have travelled to 

 unexpected grounds. 



100. In vol. vii. of the Pacific Eailroad Eeports, part 2, is the Geological 

 Eeport, presented to the Hon. Jefierson Davis, then Secretary of War, by 

 Thos. AntiseU, M.D. He states reasons for believing that during the Eocene 

 period the Sierra Nevada only existed as a group of islands ; that its final 

 uplifting was after the Miocene period ; and that during the wbole of that 



80 



