490 Section by the Portillo Pass. paet n. 



masses, for we shall afterwards see in the Cumbre Pass 

 that the gypseous and intercalated beds are lens-shaped, 

 and that they thin out, even where very thick, and 

 disappear in short horizontal distances : it is quite 

 possible that the black shales and red sandstones may 

 be contemporaneous, but it is more probable that the 

 former compose the uppermost parts of the series. 



The fossils above alluded to in the black calcareous 

 shales are few in number, and are in an imperfect 

 condition ; they consist, as named for me by M. d'Or- 

 bigny, of— 



1. Ammonite, indeterminable, near to A. recticostaius, D'Orbig. 



' Pal. Franc' (Neocomian formation). 



2. Gryphaea, near to G. Couloni (Xeocomian formations of France 



and Neufchatel). 



3. Xatica, indeterminable. 



4. Cyprinarostrata, D'Orbig. 'Pal. Franc.' (Neocomian formation). 



5. Eustellaria angulosa(?) D'Orbig. 'Pal. de l'Amer. Mer ' 



6. Terebratula? 



Some of the fragments of Ammonites were as thick 

 as a man's arm : the Gryphaga is much the most 

 abundant shell. These fossils M. d'Orbigny considers 

 as belonging to the Xeocomian stage of the Cretaceous 

 system. Dr. Meyen, 1 who ascended the valley of the 

 Rio Yolcan, a branch of the Yeso, found a nearly 

 similar, but apparently more calcareous formation, with 

 much gypsum, and no doubt the equivalent of that 

 here described : the beds were vertical, and were pro- 

 longed up to the limits of perpetual snow : at the height 

 of 9,000 feet above the sea, they abounded with fossils, 

 consisting, according to Yon Buch, 2 of — 



1. Exogyra (Gryphaea) Couloni, absolutely identical with specimens 



from the Jura and South of France. 



2. Trigonia costata, 1 identical with those found in the upper 



3. Pecten striatus, Jurassic beds at Hildesheim. 



1 ' Eeise urn Erde,' Th. 1. S. 355. 



2 ' Descript. Phys. des lies Canaries,' p. 471. 



