-
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...
- and a
ventral and
marginal siphuncle.
Septal necks are
orthochoanitic ventrally and
orthochoanitic or
cyrtochoanitic dorsally. The
Aipoceratoidea are the...
-
orthoconic to cytroconic, with long but
variable camerae,
siphuncle with
orthochoanitic septal necks and
tubular segments, and
generally straight sutures. Ascoceratinae...
- rear. Siphuncle: small,
slightly ventral of the center,
thought to be
orthochoanitic (straight
septal necks) and
cylindrical (tubular
connecting rings)....
-
Proteoceratidae begin cyrtochoanitic with
expanded segments and end up
orthochoanitic with
subcylindrical segments. As
juveniles they are "pseudorthoceratoid"...
- by
distinct shallow grooves. The
siphuncle is subcentral,
apparently orthochoanitic. Sweet,
Walter C. 1964. Nautiloidea-Orthocerida.
Treatise on Invertebrate...
-
close to the venter,
composed of
straight and
empty segments, i.e.
orthochoanitic.
Bernhard Kummel 1964. Nautiloidea-Nautilida
Treatise on Invertebrate...
