Bellerophon (genus)
Bellerophon is a genus of extinct paleozoic marine molluscs of uncertain position (Gastropoda or Monoplacophora) in the family Bellerophontidae. The genus was named after Bellerophon, the ancient Greek hero. "Bellerophon" is the type genus of the family Bellerophontidae. Shell description. The genus is characterised by a shell which is globose, convolute, and planispiral (symmetrically coiled). The shell of "Bellerophon" superficially resembles that of a miniature cephalopod (e.g. "Nautilus" or an ammonite), except that septa are lacking. The shell of "Bellerophon" is often a couple of centimeters in maximum dimension. The external surface is smooth, ornamented only by growth  lines. There is a low crest or ridge running along the midline of the shell. Many specimens of "Bellerophon" show something resembling a "waterline" about halfway up the shell, suggesting that a large amount of the mantle and foot were exposed and covered the outside of the shell, as in the extant Cypraeidae and Naticidae. Possible life habits. These animals were probably quick moving (for gastropods), relying on speed to avoid predators and, when this was not possible, withdrawing deeply into the shell. Range of distribution. The genus occurs worldwide, and is known from the Silurian to the Early Triassic  periods. Discussion of the taxonomy. Although usually classified as a primitive gastropod, there is a minority view that the Bellerophontida actually represented a more primitive, untorted type of mollusk, (see Torsion) which evolved a spiral shell independently. Another view is that some Bellerophontids, including "Bellerophon", were torted gastropods, but that others were untorted forms. Species. Species within the genus "Bellerophon" include: subgenus "Bellerophon" subgenus ?