364 Prof. J. Orton on the Geological 



Titicaca 12,500 feet ; and Raimondi has found Carboniferous 

 rocks on the Apurimac at the height of more than 14,000 feet. 

 It is evident that through the Palaeozoic ages at least the basin 

 of the Amazons was an open sea*. 



No*Mesozoic rocks are visible east of the Andes, except 

 the Cretaceous conglomerate found by Chandless on the 

 Upper Puriis, which, however, was evidently washed down 



* A pebbly bottom is first struck in ascending the Ucayali about fifteen 

 miles up the Pachitea. Now and then blurts of yellowish-grey sandstone 

 abound on the Pachitea ; but the Ucayali, for 700 miles from its mouth, 

 flows through a vast pampa, overflowed in the rainy season. The rocky 

 bed of the Pichis (lat. 10°, lonor. 75°) is filled with fragmentary fossiliferous 

 limestone of an ash-grey colour. At Puerto Tucker, the highest point 

 navigable in canoes, lofty mountains are seen about seven miles distant, 

 extending east and west. I am indebted to the Hydrographical Commis- 

 sion for specimens from the bed of the Pichis. Among them are two 

 corals, which I have submitted to Professors Hall and Pourtales. One 

 is cyathophylloid, having the structure of Amplexus ; but it is com- 

 pound. The other has the aspect of Syringopora, and may be an Edrio- 

 phyllum of small size. The evidence is in favour of their Carboniferous 

 age. The following note on the mollusks is by Mr. Orville A. Dewey, of 

 Cornell University : — " On his return from Peru in 1874, Prof. James Orton 

 submitted to me for examination a piece of fossiliferous limestone from 

 the Pichis river. The mass was a waterworn pebble of dark-blue stone, 

 scarcely larger than one's fist. The fossils being silicified, the specimen 

 was treated with acid, and a number of species of Brachiopoda obtained. 

 The only other fossil was a slender ramose coral or Bryozoan, which, being 

 imperfectly silicified, could not be obtained for identification. The number 

 of individuals and species occurring in so small a mass indicate an ex- 

 ceedingly rich fauna in the locality. The following are the species de- 

 termined : — 



" Spirifera camerata, Morton : this widely distributed species is 

 represented by several specimens, one of which is of considerable size, and 

 shows unmistakably the characteristics of the species ; the fasciculated 

 arrangement of the ribs, though distinct, is not strongly marked ; and in 

 this as in other respects it agrees with the forms found on the Tapajos. 

 The occurrence of this form in the Andes strengthens the view which I 

 had taken in my paper on the Brazilian Carboniferous Brachiopods (Bull. 

 Cornell Univ. vol. i.), that & condor, D'Orb., from Lake Titicaca is identical 

 with the North-American species. Spirifera or Spiriferina, sp. : 

 there is also a fragment with rather coarse simple ribs not recognizable 

 specifically ; the aspect is that of a Spiriferina ; but no puncta have been 

 observed. Spirifera perplexa, M'Chesney-: a single dorsal valve is 

 referred to this species. In the paper above cited I have endeavoured to 

 show that this well-known and widely distributed American form is 

 distinct from the European S. lineata, Martin, to which it has usually been 

 referred. An exceedingly small specimen, presenting the characters of a 

 smooth Spirifera, is probably the young of this species or of S. plano- 

 convera, Shumard. Epmetria Mormonii, Marcou (Retzia pimctidifera, 

 Shumard), is by far the most abundant species, being represented by ten or 

 a dozen specimens in the rock examined ; one of these is figured on pl.viii.fig. 8 

 in my paper referred to. Terebratula bovidens, Morton (?) : a crushed 

 specimen agrees perfectly with Morton's species from Missouri in the cha- 

 racters of the beak and in general form, as far as the latter can be observed. 

 This species is known from two Bolivian localities. Salter identified it, 



