The occurrence of the fossil horse and of Mastodon angiis-
ildcns in South America, is a much more remarkable circumstance
than that of the animals mentioned above in the northern
half of the continent; for if we divide America, not by the
Isthmus of Panama, hut by the southern part of Mexico,* in
lat. 20°, where the great table-land presents an obstacle to
the migration of species, by affecting the climate, and by
forming, with the exception of some valleys and of a fringe
of low land on the coast, a broad barrier ; we shall then have
two zoological provinces strongly contrasted with each other.
Some few species alone have passed the barrier, and may be
considered as wanderers, such as the puma, opossum, kinkajou,
and peccari. The mammalogy of South America is
characterized by possessing several species of the genera of
llama, cavy (and the allied animals), tapir, peccari, opossum,
anteater, sloth, and armadillo. If North America had possessed
species of these genera proper to it, the distinction of
the two provinces could not have been drawn ; hut the presence
of a few wanderers scarcely affects the case. North America,
on the other hand, is characterized by its numerous rodents,!
and by four genera of solid horned ruminants,! of which
section the southern half does not possess a single species.
w h e th e r from w e s t to e a st, o r th e rev e rs e . P e rh a p s , w h e n w e re c o lle c t
h ow e x tr a o rd in a rily th e P a c h y d e rm a ta a b o u n d e d d u r in g th e T e r tia ry
ep o c h s in th e O ld W o rld , a n d t h a t th e rep r e s e n ta tiv e s o f th e s e a n im a ls
n ow o n ly e x is t in th a t q u a r te r , i t m ay seem m o s t p ro b a b le t h a t th e
m ig r a tio n to o k p la c e from A s ia to A m e ric a .
T h is is tlie d iv is io n fo llow ed b y L ic h te n s te in , Sw ain so n , a n d R ic h a rd so
n . T h e s e c tio n from V e ra C ru z to A c a p u lco , g iv en b y H um b o ld t in
tlie A tla s to P o lit. E s say o n K in g d om o f N . S p a in , will sh ow h ow im m
en s e a b a r r ie r th e M e x ic a n ta b le -la n d forms.
! D r . R ic h a rd s o n (R e p o r t to B r it. A sso c ., p . 157), t a lk in g o f th e
id e n tific a tio n o f a M e x ic a n a n im a l w ith th e Synetheres prehensUis, says,
“ W e d o n o t k n ow w ith w h a t p ro p rie ty , b u t, i f c o rre c t, i t is, i f n o t a
s o lita ry in sta n c e , a t le a s t v e rj' n e a rly so, o f a r o d e n t a n im a l b e in g com m o n
to N o r th a n d S o u th A m e ric a .”
! Dicranocerus furcifer, Capra Americana, Ovis montana. Son Americana,
a n d Moschatus.— R e p o r t to B r i t. Assoc., p . 159.
JÎ, ■
This distinction of the two zoologicai provinces does not
appear always to have existed. At the present day tlie
order of Edentata is much more strongly developed in South
America, than in any other part of the world: and concluding
from the fossil remains, which were discovered at Bahia
Blanca, such must have been the case during a former
epoch. In America, north of Mexico, not one of this order
is now found: yet, as is well known, the gigantic megalonyx,
considered by Cuvier as a species of Megatherium, has been
found only in that country; and as it appears from recent
observations,# the Megatherium Cuvierii itself likewise
occurs there. Mr. Owen showed me the tibia of some
large animal, which Sir Philip Egerton had purchased
out of a collection of the remains of the mastodon brought
from North America. Mr. Owen says it certainly belongs
to one of the Edentata, and it so closely resembles a bone
which I found embedded, together with fragments of the
great armadillo-like covering, in Banda Oriental, that it
probably forms a species of the same genus. Lastly, among
the fossils brought home by Captain Beechey from the
N.AV. coast, there was a cervical vertebra, which, when compared
by Mr. Pentland! with the skeletons at Paris, was
found to resemble that of the sloth and anteater more than
that of any other animal, although having some points of
essential difference.
Of the Pachydermata four or five species are now found in
America; but, as in the case of the Edentata, none are
peculiar to the continent north of Mexico; and one alone
seems to exist there as a wanderer. Yet the account of the
multitude of hones of the mastodon and elephant, which
have been discovered in the salt-licks of North America, is
familiar to every one. The remains of the Mastodon gigan-
teum have been found nowhere else; but those of the
Elephas primigenius are common to a large part of the
* E d . N ew P h il. .Tournal. J u ly , 1828, p . 3 2 7 . F rom a p a p e r b y Mr.
C o o p e r in th e L y c e um o f N a tu r a l H is to ry o f N ew Y o rk .
f S e e D r , B u c k la n d . A p p e n d ix to B e e c h e y ’s Vo y ag e, p . 5 97.
ÏL. i !
M.
L