DISTRIBUTION 1N TIME AND SPACE 123;
j
this time, according to Wegèner, thatthe,northern parts of
'
‘
America and Europe beganl‘to:separate;from each other,
and it is certain that the physical
'aCCompanying
=
the-separationc0ntributed to the extinctionprmmyrœm
'
and the isolation of
'
another form that seemsto haVe been
up to the Miocene period,
it is “now
,
,
some four species in North America,ianging fromthe'Great
»
'
Lakes _southwards to Mexico and.Cüba, and by
in China(]ordan and
…
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f
,
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Whilst the pelagic typeWas thus sending off a
forms that settled down to
or’le‘ss s€detarÿïodé
,
“
—_
of life in the lahd—lockecl— Waters o£the northern hemisphere ,
1
from China to America',Îwe cannotsupp08e‘ that it was less = Ÿ j
,
active in spreading outint0
UnlesS they
Ï
occasionally approa'ched the coasts, however, or were caught
'
‘
in amore
elevationpf the land, they would
'
-
not occur inthe ge010gical depoSits;liThè
seems to fhaŸeïb‘eenr—of
deposits
,
.
Î
_
—
America-and
forms,î(‘QîOSP1-lYïæä£
’
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for
,
…
dàÿf—» » : . -' =i
,
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Inadd1üontothepelaglc
: 'Çhpôid‘tÿPèäf
thePalæozomwaterscontamedanotherwhlmwühæme
\,
reason 5 has been ’
-
the j»forerun”ner(ofthe trueSharks
Ï5
5
The long fusifôrrn body of Acahthodes With'hetèr0Cëfë31ÏË—Îail—
shows that it was a
and this is alsoindi‘cated
ï
_
-
by the cutwater spines in front of thens.- In'shape
of ‘
,
__
body and position of the latter it was similar to Palæoniscus,
_
butthe gills were free and the body covered with the plaCoid .
dènticlesof the‘modern
Acanthodes still retained , -
, ,,
menibranecalcications, however, in relation Withthe_1aWS
:_ and roof
'
of: the Sküll,‘ eÿen the pectoral g1rdleWäSpary ?
ossied=
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,
;
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