350 ORIGIN OF LIFE IN AMERICA 



into the adjoining state of Arizona. The second lives in 

 Ecuador and Peru. The third is only met with in Chile and 

 southern Peru. They all are entirely confined to the west 

 coasts. A somewhat more distant relationship exists between 

 the centipede Newportia of the West Indies and Central and 

 South America, and Plutonium, which is confined to Sardinia 

 and Corsica. This affinity implies the presence of a former 

 mid-Atlantic land bridge between the Mediterranean and 

 Antillean Eegions and between the latter and northern South 

 America. 



My principal aim, in alluding to the fauna of Ecuador 

 and the adjoining areas, was to point out the more im- 

 portant features of the former as an ancient land-mass 

 somewhat independent from the rest of South America, 

 and the affinity of its animal inhabitants with those 

 of Central America, the Antilles and even southern 

 Europe. The antiquity of the region can be demonstrated by 

 many examples. Even birds show it clearly. Among one 

 hundred and eighteen genera of humming-birds (Troohilidae) 

 known to science, Androdon, Eutoxeres, Damophila, Uro- 

 chroa, Phaeolaema, Agapeta, lonolaema, Eugenia and others 

 are quite confined to this region.* Among mammals I need 

 only mention the remarkable discovery by Mr. Oldfield 

 Thomas f of Caenolestes. This small rat-like mammal in- 

 habits Ecuador and the province of Bogota in the adjoining 

 State of Colombia. It is, therefore, quite confined to north- 

 western South America. The only other known genera of the 

 family Epanorthidae were found in the Santa Cruz deposits 

 of Argentina. The presence of a still living member of this 

 otherwise extinct family is of considerable interest. Even 

 more important is the fact that Caenolestes is the only living 

 American herbivorous marsupial mammal more nearly related 

 to the kangaroo of Australia than to the American representa- 

 tives of the order the opossums. 



The only South American representative of the family of 

 bears (Ursidae) known as the spectacled bear (Tremarctos 

 ornatus), on account of the yellow rings surrounding its eyes, 



* Hartert, E., " Trochilidae." 

 t Thomas, O., " On Caenolestes,' 1 



