Loosely coiled; early whorls typically irregularly helical; later whorls with several, more or less straight shafts in one plane, but some are helical throughout. Ventrolateral tubercles normally on at least some ribs and commonly lateral tubercles as well.
Genus: Protanisoceras SPATH 1923
Type species: Hamites raulinianus d'Orbigny, 1842
Coiled in open spiral, in one plane or slightly helicoid, with terminal hook or with several more or less straight shafts; ribs rectiradiate, weak or absent on dorsum, with ventrolateral and in some species midlateral tubercles on some or all ribs; ribs joining tubercles across venter may be flattened but not doubled.
Subgenus: Protanisoceras (Protanisoceras)
Shaft and body chamber hook coiled in same plane
Protanisoceras [Protanisoceras] ventrosum, Casey, 1960
Protanisoceras [Protanisoceras] alternotuberculatum, (Leymerie)
Subgenus: Protanisoceras (Torquistylus) CASEY, 1961
Bluntly ribbed, with body chamber rolled over to one side, twisting ribs

Protanisoceras [Torquistylus] anglicum, Casey, 1961

Subgenus: Protanisoceras (Heteroclinus) CASEY, 1961
Like P. (Protanisoceras) but with more or less prolonged, helicoid beginning, slightly fibulate lateral ribs and tubercles, and larger umbilical lobe in suture
Protanisoceras [Heteroclinus] nodosum, Casey, 1960
Protanisoceras [Heteroclinus] flexuosum, (d'Orbigny, 1842)
Genus: Metahamites SPATH 1930
Type species: Hamites sablieri d'Orbigny, 1842
with three subparallel shafts; ribbing on phragmocone oblique; fine or almost obsolete; ribs of phragmocone on and between periodic, strong folds or with periodic, large flat spine bases covering several ribs; on body chamber ribs bolder and distant; tuberclesw, if persisting, covering only 1 rib. Suture more florid than in Protanisoceras.
Metahamites sp.
Genus: Anisoceras PICTET, 1854
Type species: Hamites saussureanus PICTET, 1847
Differs from Protanisoceras primarily in its more helicoid coiling, fibulate ribbing, and more complex suture with regularly bifid L and U; occasional subtrifid lobes occur.
Anisoceras subarcuatum Spath 1938
Genus: Idiohamites SPATH 1925
Type species: Hamites tuberculatus J. Sowerby, 1818
Coiling rather irregular, in one plane; ribs radial or oblique, with a pair of ventral tubercles joined normally only by single rib on venter; lateral tubercles rarely present.
Idiohamites tuberculatus (J. Sowerby 1818)
Idiohamites ellipticoides Spath 1938
Idiohamites favrinus (Pictet 1847)


Wright C.W. 1996. Treatise on Invertebrate Paleontology; Part L MOLLUSCS 4 Revised (Volume 4: Cretaceous Ammonoidea)



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