LOCOMOTION IN GASTROPODS
'
165
Tectarius, as already noted, practically fulllsthesrä conditions
except that its waves are retrograde. This general theory of
the mechanics of gastropod locomotion is an elaboration of the
,
views already set forth by Jordan (’01).
,
'
'
It is not my purpose
in this paper to enter into an account of
the musculature by which the movements already described are
_
carried out, forl have made no observations on this part of the
,
'
subject.
It is, however, pertinent to show that “the elements of
motion implied in the preceding description are not inconsistent
' _
with the general structure of the—snail’s foot.
The workof Jor—
dan (’01), Biedermann (’05), and others shows conclusively, ][
believe, that the musculature of the snail’s foot works against
'
' _
the elastic—waed, uid—lled cavities of the animal’s interior
,
and that these cavities are often temporarin closed from one
another.
It is these spaces which, acting collectively as a vacuo—
'
lated, erectile tissue, give rise to such rigidity as is possessed by
»
the expanded foot of the snail.
_
In this tisSue two sets of muS—
,
,
cles, longitudinal and dorso—ventral, have been identied. rIjhe
dorso—ventral .muscles lift the foOt loèally from the substratei_
They are imbedded in the vacuOlated tissue alreadymentioned
jÏ
and when they contract, their dorsal ends, being more ‘rmly
set than their ventral ones,
as relatively_- xed points and
-
_
the ventral ones, therefore, move:
Support
that
these muscles receive ,‘comes primarily from the
to their dorsal ends whiCh inturn gets its support ;from Other
.
_
tissues reachihgto the parts of the foot xed on-Ïth‘e substrate in
,
front and behind
region
The
ven_
—
;
tral end hitsthefootlocallyandmemomesadhesmnmth€gwe
I region; «Whemhe muscie1e1axesthepmù@n0fthef°0t thatWâS
elevated is returnedto1tsformerleV€lChleÿthheelaStmaCtl@n
ofthevaeuolatedüssueandtheŒUSCÏGIËCGVŒSËS°“gmaength
runsonthesurfaœefthefe@tfmmtat@h€ad
ThesecondelementmtepedalWäV18thef@fWæ“"’ement
ofthatpmtwnofthef@@twhmhlsœmpralyhe‘âmthe
'
165
Tectarius, as already noted, practically fulllsthesrä conditions
except that its waves are retrograde. This general theory of
the mechanics of gastropod locomotion is an elaboration of the
,
views already set forth by Jordan (’01).
,
'
'
It is not my purpose
in this paper to enter into an account of
the musculature by which the movements already described are
_
carried out, forl have made no observations on this part of the
,
'
subject.
It is, however, pertinent to show that “the elements of
motion implied in the preceding description are not inconsistent
' _
with the general structure of the—snail’s foot.
The workof Jor—
dan (’01), Biedermann (’05), and others shows conclusively, ][
believe, that the musculature of the snail’s foot works against
'
' _
the elastic—waed, uid—lled cavities of the animal’s interior
,
and that these cavities are often temporarin closed from one
another.
It is these spaces which, acting collectively as a vacuo—
'
lated, erectile tissue, give rise to such rigidity as is possessed by
»
the expanded foot of the snail.
_
In this tisSue two sets of muS—
,
,
cles, longitudinal and dorso—ventral, have been identied. rIjhe
dorso—ventral .muscles lift the foOt loèally from the substratei_
They are imbedded in the vacuOlated tissue alreadymentioned
jÏ
and when they contract, their dorsal ends, being more ‘rmly
set than their ventral ones,
as relatively_- xed points and
-
_
the ventral ones, therefore, move:
Support
that
these muscles receive ,‘comes primarily from the
to their dorsal ends whiCh inturn gets its support ;from Other
.
_
tissues reachihgto the parts of the foot xed on-Ïth‘e substrate in
,
front and behind
region
The
ven_
—
;
tral end hitsthefootlocallyandmemomesadhesmnmth€gwe
I region; «Whemhe muscie1e1axesthepmù@n0fthef°0t thatWâS
elevated is returnedto1tsformerleV€lChleÿthheelaStmaCtl@n
ofthevaeuolatedüssueandtheŒUSCÏGIËCGVŒSËS°“gmaength
runsonthesurfaœefthefe@tfmmtat@h€ad
ThesecondelementmtepedalWäV18thef@fWæ“"’ement
ofthatpmtwnofthef@@twhmhlsœmpralyhe‘âmthe