NO. 2270. MIOCENE FOSSIL PLANTS FROM PERU— BERRY. 281 



change in the coastal flora. At Puerto Bolivar, in the Ecuadorian 

 Province of Eloro, the mangrove belt extends inland from the beach 

 for about 2 miles. The " mangle chico " fronts the sea and passes 

 gradually into the "mangle grande," where the Rhizophores are TO 

 or 80 feet tall and draped with Tillandsia. In the rear of the zone of 

 tall mangrove the swamp becomes more open, with small trees of 

 Rhizophora, Lagimcularia, and Avicennia, and scattered areas of the 

 shrubby Salicornia peruviana. At about 2 miles from the sea the 

 SAvamp passes over into a region of naked, sun-caked, and salt-in- 

 crusted mud flats traversed by salt-water creeks bordered by low 

 shrubby Rhizophora, Avicennia^ and Salicornia. These mud flats, 

 submerged only by the spring tides, form a belt here somewhat over 

 a mile in width, and pass gradually into the sandy arid saliferous 

 Machala plains with cacti, Prosopis^ and scattered thorny shrubs and 

 dwarfed trees. 



A good account of the estuary flora of the Santa Rosa River near 

 Puerto Bolivar is given by Guppy.^ From this point northward to 

 the head of the Gulf of Guayaquil the vegetation passes by degrees 

 into the normal tropical estuary flora. Villavicencio, Wolff, Web- 

 ster, Guppy, and others believe that the costal region is still becoming 

 progressively more sterile, and since Darwin's day we have had evi- 

 dence of coral masses and elevated shell beds pointing to a former 

 lower level of the land and, presumably to be correlated with this, a 

 more humid climate. Suess suggested - that this might be due to the 

 formation of the Isthmus of Panama and the appearance of the 

 Plumboldt current. Since, however, the waters of the Atlantic and 

 the Pacific have freely mingled at many times during geologic his- 

 tory, and as we as yet Imow comparatively little of the Tertiary his- 

 tory of South America, it is not possible to discuss these interesting 

 problems with profit. 



Aside from the description of a few species of Tertiary marine fos- 

 sils by d'Orbigny,^ Nelson,* and Gabb,^ the general work of Rai- 

 mondi,*^ and incidental references in Darwin's Voyage of the BeagleJ 

 the only detailed accoimt of the geology of any locality in this part of 

 Peru is based on a reconnoissance of Josef Grzybowski, of Cracow, 

 who spent a week around Tumbez and Paita in 1898 and who sub- 



> A Naturalist in the Pacific. 



^ Das Antlitz der Erdo, vol. 2, p. 825. 



^ d'Orbigny, A., Paluontologie due Voyage I'Anierique m(;rldionale, Paris, 1842. 



* Nelson, E. T., On the Molluscan fauna of the later Tertiary of Peru. Trans. Conn. 

 Acad., vol. 2, pt. 1, 1870. 



= Gabb, W. M., Description of a collection of fossils, made by Dr. Antonio Raimondl in 

 Peru, Journ. Acad. Nat. Sci.. Phila., ser. 2, vol. 8, pp. 203-336, pis. 35-43, 1877 



• Raimondl, A., El Perfl, vol. 4, Estudifis miueralogicos, Lima, 1902. 



' Although devoted to the region farther south, the recently published work by Bowman 

 on The Andes of Southern Peru (Amer. Geogr. Soc, 1916) gives an admirable discussion 

 of the broader aspects of the physiographic history and climatic features of the Peruvian 

 region. 



