591. EE?oiiT— 18C3. 



Mtja Moniereymm. Conr., p. 313. [Figure resembles Periploma 



arf/enturia.l Monterey Co. 

 ?Mi/a siilm/itiafa, Conr. [Conip. Macoma inquinata.'] Monterey Co. 

 Arcopaf/ia nwdialu, Conr., p. 314. Like A. hip/icufa, Conr.. of 



the Maryland Miocene. [Closely resembles Lutricola alia, Cour.] 



Monterey Co. 

 Tapes liuteattwi, Conr., p. 314. California. 

 Area rinalis, Conr., p. 314. Santa Barbnra. 

 Area triliiuata, Conr;, p. 314. S;inta Barbai"a. 

 Area congesta, Conr., p. 314. California. 



Axincea Barbarensis, Conr. [Clos-ely resembles Tect. tHtermriliii.i.'] 

 Mulinia denmta, Conr., p. 313. ? tianta Barbara and sLoies ot 



Pablo Bay. 

 Dosinia lmi(pda, Conr., p. 315. Monterey. 

 Dosinta alia, Conr.. p. .315. Monterey. 

 Peeten Pahioeitsis, Conr. San Pablo Bfiv. 

 Pallium Egtrellnnum, Conr., p. 313. Estrella Valley. 

 Janira hella, Conr., p. 312. Santa Barbara. • 



I- Ostrea Titan, Conr., Phil. Proc. 1855. San Luis Obi?po. 



Pandora bilirata, Conr., p. 267. [Closely resembles Kmnerlia 



bicarinata.] Santa Barbara. 

 Cardita oeeidentalis, Conr., 1855, p. 2G7. [?= C. ventrteosa, Gld.l 



Santa Bai'bara. 

 Diadora enicibidiformis, Conr., 1855, p. 207. {? = Pmiciurella 



cueullata, Gld.] Santa Barbara. 



Fossils of Gatun, Isthmiis of JDarien. 



Malea ringens, Swains. Gatun. 

 TiirriteUa aUilira, Conr. Gatun. 

 Turritella Gatunensis, Conr. Gatun. 

 Triton, sp. ind. Gatun. 



? Cytherea Dariena, Conr. [The fipur« does not appear conspe- 

 cilic with that in the Blake collection, no. 50.] Ualun. 



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, Mnlea r'niijcnx, 

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

 many miles from the Caribbean Sea. The characters of this shell beiig such 

 as to be easily recognized, and not even the genus api)earing in the Atlantic, 

 it is fair to conclude that it had migrated from its head waters in the Paciilo 

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

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

 when the present se})aration between the two oceans did not exist. T\'o 

 may conclude that species as old in creation as Malea riiu/ens 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 Uailroad Reports, part 2, is the Geological 

 Keport, presented to the Hon. Jeft'erson Davis, then Secretary of War, by 

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

 period the Sierra Nevada only existed as a group of i.slands; that its final 

 Uplifting wad after t?ie Miocene jif'iod ; aud that during the whole of that 



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