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 Regions 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, Ionolaema, 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., “ Trockilidae.” 
t Thomas, O., “ On Caenolestes. ” 
