GEOLOGY OF PERU—ADAMS. 401 
D’Orbigny discussed the occurrence of the Cretaceous in South 
America, and in his section shows an extension of porphyritic rocks 
on the west slope of the Cordillera Occidental; he did not differ- 
entiate the Cretaceous, but evidently included them with the por- 
phyries with which they are interbedded. 
In the section which Forbes made from Arica to Bolivia he classi- 
fied (1861) as oolitic (Liassic) the rocks at Arica, which he describes 
as shales, claystones, and embedded porphyries, and stated as his rea- 
son for doing so that to the south of the district which he studied 
the rocks are abundantly fossiliferous and had yielded to the re- 
searches of Bayle and Coquand and Phillipi about 35 species of 
recognized oolitic forms. On his map he showed a considerable ex- 
tent of oolitic in the Cordillera Occidental of southern Peru. 
Apparently, Raimondi attempted to identify the fossils which he 
collected, although he did not describe them. He evidently used the 
fossils as a guide in determining as best he could the age of the sedi- 
mentary formation, which he discusses in his various writings. When 
he sent his collections to Gabb to be described he accompanied them 
by a letter (1867) in which he outlined the geographical distribution 
of the sedimentary formations of Peru. According to his idea, 
Cretaceous (with Jurassic, Lias, and Trias) is distributed principally 
in the western Cordillera. He thought the stratified rocks near the 
Port of Ancon, at San Lorenzo, near Callao, and at Chorillos, to be 
Jurassic or Liassic. These localities have since proven to be Creta- 
ceous, aS will soon appear in this paper. Unfortunately, Gabb’s de- 
termination of the Mesozoic fossils was delayed and, moreover, he 
did not give to them such diagnostic value as would help Raimondi to 
revise his ideas in his later writings. 
In his volume on the Department of Ancachs he classed (18738) as 
Cretaceous certain limestones with echinoderms, oysters, and other 
fossils. This seems to be correct as viewed in connection with the 
determination of the Cretaceous in other localities, where it con- 
sists largely of limestone and contains similar fossils. 
In his geological sketches (1876) Agassiz states that Mr. William 
Chandless, upon his return from the River Purus, presented him 
with fossil remains of the highest interest and undoubtedly belong- 
ing to the Cretaceous. They were collected on the River Aquiry, 
latitude 10°-11° south, longitude 67°-69° west, in localities varying 
from 430 to 650 feet above sea level. Among the material, remains 
of a Morosaurus and of fishes were found. Chandless¢ says that the 
material identified by Agassiz consisted of two perfectly preserved 
vertebree of Morosaurus. These are the only vertebrate remains thus 
a2“ Notes on the River Aquiry, the principal affluent of the Purus,” William 
Chandless, Journal Royal Geogr. Soc., Vol. 36, p. 119. 
