BELO'PTERA, a genus of Fossil Mensal, established by Deshayes and described by De Blainville as an animal entirely unknown, containing in the back part of its muscular envelope a symme trical calcareous or bony shell formed of a thick solid summit very much loaded behind, and a front tube more or less complete, the cavity of which is conical and annular, the shell or bone having wing-shaped appendages without any anterior shield-like prolongation.
De Blainville divides the genus into two sections. The first consists of species whose wing-shaped appendages are united below the summit, and whose cavity is somewhat in the shape of a scuttle (hotte). Of this section Beloptera sepioidea is given as an example.
The second includes species whose wing-shaped appendages aro distinct, and whose cavity is completely conical with traces of chambers and of a siphon. Of this division Beloptera belonnoidea is given as an illustration.
De Blainville observes that this genus ought to be placed at the end of the Sepiad(r, or Cuttles ; and that the first of the species is evidently very much allied to tho bones of those animals, while the second approaches the Belemnites.
After all, the probability is, that these bodies are only por tions of the bones of some of the Cuttle-Fishes ; and this appears to • have been the opinion of Cuvier.
If a perfect bone of the common species of our coasts be closely examined, a structure very analogous to the conical circularly-grooved cavity of Beloptera, although in a more expanded form, will be observed. These fossils have been found in the London Clay, and other beds above the Chalk.
Voltz, in his Memoir on Belemnites, makes Beloptera se* idea a distinct genus under the name of Beloscepia.