400 Al^NUAL EEPORT SMITHSONIAN INSTITUTION, 1908. 



rocks were classed by d'Orbigny as Devonian and Carboniferous and 

 in part Triassic, but he cited no fossils. Forbes says that the beds 

 contain plant remains (coniferous indeterminable) and he was in- 

 formed that a complete Saurian head had been extracted from the 

 beds by M. Ramon Due, but was not successful in obtaining it nor 

 some fossil bones and teeth now in the Museum of Avignon in France, 

 sent there by M. Granier of La Paz. The character of these beds, as 

 already stated in describing the Permian, is like the typical Permian 

 of Russia. Forbes concluded that their age must await the finding 

 of fossils. 



Raimondi (1873), in his study of the Department of Ancachs, 

 classes as Jurassic certain formations containing coal and yielding 

 ammonite fossils. However, he had no other determination for his 

 fossils than that furnished by Gabb, which was not very critical and 

 so we must rely on later work for the differentiation of the Jurassic. 

 It will be seen later that the plants and invertebrates from the coal 

 horizon of the Cordillera Occidental have been shown to be Creta- 

 ceous. However, Raimondi in some instances was j^robably correct in 

 assigning formations to the Jurassic, since it is now known to be pres- 

 ent and has yielded numerous fossils. Bravo has called attention to 

 the fact that Gottsche"^ has made mention of an ammonite from 

 Morococha which is in the Freiburg collections. 



Fossil ammonites from Huallanca, in the Department of Ancachs, 

 collected by Durfeldt and belonging to the Freiburg Museum, were 

 studied by Steinmann (1881) and considered by him as indicating 

 the Tithon (which is homotaxial with the Portlandian) and belong- 

 ing in the upper part of the Jurassic. 



CRETACEOUS. 



The island of San Lorenzo at Callao was examined by Dana, and 

 his description is published in the report of the Wilkes expedition 

 (1849). He made some detailed sections of the rocks and found 

 some fossils which he considered as indicating the oolitic. He refers 

 in a footnote to the fact that James Delafield had reported ^ up)on 

 some fossils which Doctor Brinkerhoff had collected from the island 

 and presented to the New York Lyceum of Natural History. Dela- 

 field did not venture an opinion as to the age of the fossils. 



Doctor Pickering, who was with Dana, found an ammonite at the 

 head of the Chancay Valley at an elevation of 15,000 feet in rocks 

 similar to those of San Lorenzo Island. This specimen is described 

 in the appendix of the report as Ammonites pickeringi. Some fos- 

 sils from Trujillo are also figured. 



* Uber Jurassiche versteinerungen aus der Argentinisclie Cordillere. Dr. 

 Carl Gottsche, Cassel, 1878. 



^ Amer. Journ. Sci., Vol, 38, p. 201, 1839. 



