278 Reviews — Dr. C. Burckhardt—Aryeiitino- Chilian Cordilleras. 



yielded fossils; and the same to a certain extent is the case with 

 Oxfordian (as limited by the author) and Rauracian, though we 

 should in this country from the presence of Cardioceras Lamberti 

 recognize portions of our Oxfordian. The strata which occur below 

 the Kimeridgian are largely formed of gypsum, red marls, grits, 

 and conglomerates, and they indicate at any rate somewhat altered 

 conditions. 



The identification, or approximate identification, of many South 

 American fossils with European species is comforting, for it enables 

 comparisons to be made much better than if distinct ' specific' names 

 had been given ; and as the sequence of the forms is the same in the 

 two areas we cannot doubt that approximate correlation is justified. 

 There appears to be a blending of Kimeridgian and Tithonic forms 

 in the Lower Tithonic. 



The following table shows the grouping and the leading fossils 

 noted by Dr. Burckhardt : — 



Neocomian \ ( Exogyra Couloni, Defr. 



and > ... ... \ Lytocer as ci. subfimhriatum, &'Oxh. 



Bereiasian ) ( MopUtes aff. occitanicus, Pict. 



I Upper ... Odontoceras permulticostatum, Steuer. 

 liTHONic (TnTyp,- ( Oppelia pe^iceris, Steuev. 



Kimeridgian ... '. " ( ^ Ferisp/nnctes coluhrmus, Eein. 



( Fensplnnctes pohiplocus, Keiu. 



Eauracian I (Not yet distiiiTOished by fossils.) 



Oxfordian j \ i a : i 



{Cardioceras aff. Lamberti, Sow. 

 Peltoceras athleta, Phil. 

 Perisphinctesfiinatus, 0pp. 

 Bathonian ... ... (Not yet distinguished by fossils.) 



! (Upper zones not yet distinguished.) 

 Sonninia aff. Soiverbiii, Mill. 

 Amnsium (Fecten) personatum, (jtoIqi. 

 Harpneeras opaliniim, Rein. 

 J ( Upper ... (U])per beds united with Lower Bajociau.) 



'" \ Middle ... AmaWieus spinatus, Brug. 



Between the Neocomian and the Senonian there are strata which 

 have furnished no determinable fossils, but as the ibrmations do not 

 exhibit discordance the author thinks the sequence may be complete. 

 In the Senonian Gryphaia vesicidaris, Lam., and Plicatula aff. multi- 

 costata, Forbes, are noted ; and in the Danian, Turritella Soaresana, 

 Hartt, and Cardita Morganiana, Rathb. — the Turritella being near 

 to T. ventricosa, Forbes, and T. multistriata, Reuss. 



A remarkable fact about the region is that the strata are com- 

 paratively little disturbed and plicated ; and it thus differs greatly 

 from Alpine regions in the absence of dislocated portions of 

 formations and of any central massif of ancient rocks. In some 

 respects th.e structure is more like that of the Swiss Jura, from 

 which, however, it is distinguished by the presence of diorites and of 

 extensive neo-volcanic rocks. In the Jurassic series, ranging from 

 the Lias to the Tithonic, there are conglomerates, of more or less 

 porphyritic character, volcanic breccias and tuffs, which appear to 

 replace the strata at various horizons. These rocks will be described 

 in detail in the petrographic portion of the work. 



