-
middle of the body
chamber transversely constricted, and a
subcentral orthochoanitic siphuncle. The
surface is
ornamented by a
network of fine
lirae (Sweet...
- and
sutures uniformly with V-shaped
ventral lobes.
Septal necks are
orthochoanitic to cyrtochoanitic, the
apical angle may be
small or large, and the protoconch...
- (straight) but
sometimes slightly curved s****, a
central or
subcentral orthochoanitic siphuncle that is free of deposits, a long body chamber, and cylindrical...
- the long gas-filled s****.
Depending on the family, the
siphuncle has
orthochoanitic (short and straight) or
cyrtochoanitic (outwardly curved)
septal necks...
-
Flowers definition of the
Dawsonoceratidae in that the
septal necks are
orthochoanitic rather than re****bent and
siphuncle segments are
without noted constrictions...
- and a
ventral and
marginal siphuncle.
Septal necks are
orthochoanitic ventrally and
orthochoanitic or
cyrtochoanitic dorsally. The
Aipoceratoidea are the...
-
Proteoceratidae begin cyrtochoanitic with
expanded segments and end up
orthochoanitic with
subcylindrical segments. As
juveniles they are "pseudorthoceratoid"...
-
cyrtocones that
expand slightly or
moderately and have thin walled,
orthochoanitic marginal or subventral,
tubular siphuncles (Sweet 1964). The Graciloceratidae...
- by
distinct shallow grooves. The
siphuncle is subcentral,
apparently orthochoanitic. Sweet,
Walter C. 1964. Nautiloidea-Orthocerida.
Treatise on Invertebrate...
- are
typically slightly sinuous; the
siphuncle small, subcentral, and
orthochoanitic. In all the
umbilicus is open and perforate. It
includes some 17 genera...
