4-00 Tertiary Formations. paet h. 



mineralogical nature of the rocks, and from Captain 

 Belcher's minute description of the coast between Lirguen 

 and Tome, the fossiliferous concretions at this latter 

 place certainly belong to the same formation with the 

 beds examined by myself at Lirguen ; and these again 

 are undoubtedly the same with the strata of Quiriquina ; 

 moreover, the three first of the shells from Tome, though 

 associated in the same concretions with the Baculite, 

 are identical with the species from Quiriquina. Hence 

 all the sandstone and lignitiferous beds in this neigh- 

 bourhood certainly belong to the same formation. Al- 

 though the generic character of the Quiriquina fossils 

 naturally led M. d'Orbigny to conceive that they were 

 of tertiary origin, yet as we now find them associated 

 with the Baculites vagina and with an Ammonite, we 

 must, in the opinion of M. d'Orbigny, and if we are 

 guided by the analogy of the Northern Hemisphere, rank 

 them in the Cretaceous system. Moreover, the Baculites 

 vagina, which is in a tolerable state of preservation, 

 appears to Professor E. Forbes certainly to be identical 

 with a species, so named by him, from Pondicherry in 

 India ; where it is associated with numerous decidedly 

 cretaceous species, which approach most nearly to Lower 

 Greensand or Xeocomian forms : this fact, considering 

 the vast distance between Chile and India, is truly sur- 

 prising. Again, the Nautilus d 'Orbignyanus, as far 

 as its imperfect state allows of comparison, resembles, 

 as I am informed by Professor Forbes, both in its general 

 form and in that of its chambers, two species from the 

 Upper Greensand. It may be added that every one of 

 the above-named genera from Quiriquina, which have 

 an apparently tertiary character, are found in the Pon- 

 dicherry strata. There are, however, some difficulties 

 on this view of the formations at Concepcion being cre- 

 taceous, which I shall afterwards allude to ; and I will 



