1971  Umbetoceras Ruzhentsev & Bogoslovskaia: 28.
     1978  Umbetoceras.-Ruzhentsev & Bogoslovskaia: 212.

Type species: Umbetoceras uskalykense Ruzhentsev & Bogoslovskaia, 1971, p.28. [= Machangoceras YANG, 1978, p.168, type M. subglobosum, p.169; OD (subj.)].

A:   Early whorls evolute, with distinct "calyx" stage, later involute. Umbilicus moderately wide.
B-C: Sculpture consisting of strong riblets on intermediate stages; tubercles present on umbilical shoulder.
E:   Deep furrow on internal mold.
G:   Suture resembling gastrioceran type: ventral lobe wide, median saddle exceeding two third of height of entire ventral
lobe, adventitious lobe wide.

[Machangoceras has been based on one poorly preserved specimen with a subglobular conch form].

[Ruzhentsev & Bogoslovskaia, 1971, p. 28]: Shell of young specimens subcadiconic with sharp umbilical shoulder; later
ranging from subspheroconic to pachyconic: distinct calyx stage. Whorls highly involute. Umbilicus from moderately broad to
moderately narrow. Sculpture practically absent from young shells, sharp and transverse on medium shells, represented by
simple costellae, straight or slightly curved. Small tubercles along umbilical shoulder. Intraventral ridge invariably observed.
Ventral lobe well developed (wl/hl =1.20 or more).Sharply distinguished from the previously described genera by the
lack of sculpture on the early whorls, the strong development of costellae (or lamellae) on the middle stages, and such
persistent characters as the deep furrow on tubercles on the umbilical shoulder.

[Ruzhentsev et Bogoslovskaya, 1978, p.212: Conch of young specimens subcadicone, with a sharp umbilical rim.  Calyx stage distinct.  In intermediate stages of morphogeny conch is subsphaericone to pachycone, with very involute whorls and a moderately wide to moderately tight umbilicus.  Sculpture practically absent in youth.  In intermediate stages it is sharp, radial, represented by simple, straight or slightly bended ribs.  Umbilical rim has minute nodules.  There is always an intraventral keel (a deep furrow on the steinkern).  Ventral lobe well developed (w/h = 1.20 and more).]