FOSSILS OF THE IlECEKT FOllMATIOSS. 
899 
Cerro oi Tileapire ; on the [Alpine] limestone of Ciinianaeoa; 
ibetween Porto Cabello and the liio Guayguaza ; as ■well as 
in the valleys of Aragiia; on granite; on tlie western de- 
clivity of the hill iornied by Cabo Blanco, on gneiss; and 
in the peninsula ol Araya, on saliferous clay. But this is 
perhaps niorely the eliect of apposition.* li wo woidd range 
the difterent members of the tertiary series according to tbe 
age of their fonnation, we ought, I believe, to regard the 
breccia ol Cabo Blanco with Lugmeuts of primitive rocks, as 
the most ancient, and make it bo succeeded by the arena- 
ceous limestone of the castle ol Cmnana, without horned 
silex, vet somewhat analagous to the coarse limestone of 
Paris, and the Iresh-water soil of Victoria. The clayey 
gypsum, mixed with calcareous breccia with madrepores, 
cardites, and oysters, which I found between Carthagena 
and the Cerro do la Popa, and the equally recent limestones 
of Guadalo])e, and Barbadoes (limestones filled with sea- 
shells resembling those now existing in the Caribbean Sea) 
prove that the latest deposited strata of the tertiary forma- 
tion extend far towards the west and north. 
These recent Ibrmations, so rich in vestiges of organized 
bodies, furnish a vast field of observation to those who are 
familiar witli tlie zoological character of rocks. • To examine 
these vestiges in strata superposed as by steps, one above 
another, is to study the Fauna of diflerent ages, and to com- 
pare them together. The geography of animals marks out 
limits in space, according to the diversity of climates, which 
determine the actual state of vegetation on our planet. The 
geology of organized bodies, on the contrary, is a fragment 
of the history of nature, taking the word history in its 
proper acceptation: it describes the inhabitants of the earth 
according to succession of time. W e may study gener.a 
and species in museums, but the Fauna of diUbrent ages 
the predominance of certain shells, the numerical relations 
which characterize the animal kingdom, and the. vegetation 
of a place or of a period, should be studied in sight of 
those formations. It has long appeared to me that in the 
tropics as ■well as in the temperate zone, the species of uni- 
valve shells are much more numerous than bivalves. From 
* An-nieht Avflagermg, according to the precise language of th« 
geologists of my country. 
