Conus precancellatus (Macneil, 1960)
Descrizione.
Shell
small to medium sized , medium inflated , spire of medium height. Protoconch
incomplete on the type, but the last whorl and a half are conical and polished .
Aperture of even width and moderately narrow . Anal sinus shallow . Sculpture
consisting of depressed spiral grooves which are made semipunctate by fine
lattice-like cross bars, the spiral grooves being narrower than the smooth ,
flat- topped interspaces on the whorl, but as wide as or wider than the
inter-spaces on the lower part, the interspaces changing from flattened to
rounded at the base of the whorl ; spire sculptured by weak nodes along the
shoulder on the young whorls, but these disappear on the last whorls;
subsutural slope marked by crescent-shaped growth lines but no spiral sculpture
(1).
Holotype ( USNM 562876 )
measures : height 17 mm , diameter 7.8
mm.
Type locality : Shinzato
tuff member, 17633.
This species is related to C.
cancellatus Hwass, a recent species recorded from Japan ( stated by Hwass
to be from Hawaii ), but is somewhat less constricted on the lower part of the
body whorl, and lacks the faint spiral lines on the subsutural slope of the
recent species.
Conus eugrammatus (Bartsch and
Rehder, 1943 p. 85 ) , recent from the Hawaiian Islands, is also related but
lacks the fine cross walls in the spiral grooves. Like C. cancellatus, C.
eugrammatus has weak spiral lines on the subsutural slope.
This species differs from C.
cf. C. cosmetulus ( pl. 6, fig. 6 ) in having a more constricted base, no
spiral sculpture on the subsutural slope, and in having weak, irregular nodes
on its shoulder (1).
Distribution
: Miocene or Pliocene, ( Shinzato tuff member), Okinawa.
Localities : Shinzato tuff
member, 17456 , 17633 ( figured type )
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Conus precancellatusPl. 10 fig. 11 mm. 17,0 x 7,8
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Conus cancellatus
mm. 39
x 19 |
Conus eugrammatus
mm. 30,0 x 15,6
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Conus eugrammatus
Holotype
USNM 173213 mm. 30,0 x 15,6 |
Conus eugrammatus
mm. 19 Balicasag |
Conus
precancellatus
Pl. 10
fig. 11 mm. 17,0 x 7,8 |
Bibliografia