THE NEOTROPICAL REGION 83 



period. At the beginning of Pliocene time, during the 

 deposition of the Araucanian formation in Argentina and 

 the " Equus-beds" in the United States, a wide bridge 

 between North and South America, affording an easy- 

 road to migrating animals, must have existed, and this 

 again seems to have become considerably narrowed to 

 form the present Isthmus of Panama. 



List op the Principal Authorities referred to 

 in Chapter III. 



(1) Allen, J. A. — "The Geographical Distribution of North 

 American Mammals." Bull. Amer. Mtis. N.H., iv., p. 199, 1892. 



(2) Allen, J. A. — "On a Small Collection of Mammals from the 

 Galapagos Islands, collected by Dr. G. Baur." Bull. Amer. Mus. 

 N.H., iv., p. 47, 1S92. 



(3) Alston, E. R. — "Biologia Centrali -Americana, Mammalia. 

 London, 1879-82. 



(4) Chapman, F. M. — "Notes on Birds and Mammals observed 

 near Trinidad, Cuba, with remarks on the Origin of West Indian 

 Bird-life." Bull. Amer. Mus. N.H., iv., p. 279, 1892. 



(5) Cope, E. D. — " Description of two large extinct Rodents from 

 Anguilla, West Indies, with remains of human art associated." Proc 

 Amer. Philos. Soc. Philad., xi., 1871, p. 183. 



(6) Leidy, J. — " Remarks on Mylodon." Proc. Acad. Nat. Sci. 

 Philad,, 1885, p. 49. 



(7) Salvin, 0. — " On the Avifauna of the Galapagos Archipelago. ' 

 Trans. Zool. Soc, ix., p. 447 (1876). 



(8) Sclater, P. L. — "Address to Section D. (Biology)." "Report 

 of Forty-fifth Meeting of the British Association, at Bristol," p. 85 

 (1876). 



(9) Thomas, 0.— " On Some Mammals from Central Peru." P.Z.S., 

 1893, p. 333. 



(10) Trouessart, E. L. — " Note sur le rat musque (Mus pilorides) 

 des Antilles." Ann. Sci. Nat. Zool. (6), xix., No. 5 (1885). 



(11) Wallace, A. R. — " The Geographical Distribution of Animals." 

 2 vols. London, 1876. 



(12) Zittel, K. A. von. — " The Geological Development, Descent, 

 and Distribution of the Mammalia." S. B. k. bayer. Akad, Wiss., xxiii., 

 p. 137, 1893. Translation in Geol. Mag. (3), x., p. 401 (1893). 



