Ortmann —Some new marine Tertiary horizons. 479 



It seems that the total thickness of these five beds, together 

 with the intermediate, non-fossiliferous strata, amounts to sev- 

 eral hundred feet. 



Since the first and the fourth horizons contain only plant 

 remains (the fourth being the Punta Arenas coal, a very black 

 lignite, of which Mr. Hatcher has sent specimens), I shall dis- 

 regard these beds, and discuss only the horizons II, III and Y. 



Beginning with the uppermost, the fifth horizon, overlying 

 the coal mines, it is to be divided, according to the labels of 

 the specimens, into three subdivisions. Horizon Y proper 

 contains most of the fossils : but there are a number of oysters, 

 which are labelled below Y, and above Y. Thus it seems 

 that the chief horizon Y begins and ends with oyster beds. 



Now, it is very interesting that the oysters found " above Y" 

 agree in every respect with the large oyster of the Cape Fair- 

 weather beds discovered by Mr. Hatcher.* This form is not 

 found in any of the underlying beds of this section, but it is 

 represented in horizon Y and " below Y " by a form that agrees 

 completely with what I have called Ostrea philippii^ which 

 is characteristic for the Suprapatagonian beds of Patagonia 

 (Rio Chalia and Rio Chico). 



The list of the fossils found in horizon Y proper is the 

 following : 



Ortrea philippii Ortm. (= bourgeoisi Phil.) 



Pectun cuius ibari Phil. (= magellanicus Phil, -—pulvi- 



natus cuevensis v. lb.) J; 

 Lucina pro'maucana Phil. 

 Venus ehiloensis Phil. 

 Cytherea splendida v. Ih. 



Crepidula gregaria Sow. ( — Haliotis imperforata Phil. )§ 

 Lamna sp. (Tooth). 



Disregarding the sharks-tooth, we have six species in this 

 bed. Four of them {Ostrea phil., Pectuncidus ib., Venus 

 chil., Crepidtda gr.) have been recorded already by Philippi. 

 Five species {Ostrea p., Pectuncidus i., Lucina p., Cytherea s., 

 Crepidula g.) are found in Patagonia, all of them in the Supra- 

 patagonian beds, only two or three also in the Patagonian beds 



*See Hatcher, On the Geology of Southern Patagonia, this Journal, vol. iv, 

 November, 1891, p. 345, and Ortmann, On some of the large Oysters of Patagonia, 

 ibid., p. 356. 



1 no longer believe that this oyster is identical with 0. patagonica d'Orb. As 

 to the identification of the Patagonian oysters I differ from v. Ihring (Revista 

 Museu Paulista, vol. ii, 1897): but this is not the place to discuss this question 

 in detail. 



fSee 1. c, p. 356, pi. 11, fig. 2. 



% See v. Ihring, 1. c, p. 238, pi. 7, fig. 46, pi. 8, fig 50. The identity of these 

 forms is shown by our series of specimens. 



§ Haliotis imperforata of Philippi (1 c, pi. 12, fig. 2) is nothiug else than a giant 

 Crepidula gregaria. 



