Memoir 10

Part 1: Revision of Buttsoceras
Part 2: Notes on the Michelinoceratida

By R. H. Flower, 1962, 58 pp., 6 plates, 1 index.

Part I:
New material of Buttsoceras increases its range from Alabama through southern New Mexico and into northern Utah; it appears confined to the very latest phase of the Cassinian. The genus possesses a nonsegmental lining in the siphuncle, thickening gently apicad-like very slender endocones, which may terminate in a narrow tube that may be traversed by diaphragms. The inadequately known Oxfordoceras is not distinguishable from Buttsoceras; uncertainty surrounds the origin of its genotype. Buttsoceras shows fine lamellae in the lining of the siphuncle and thin homogeneous rings; it is referred to the Troedssonellidae of the Michelinoceratida. The study also involved some material referred to Michelinoceras, present with Buttsoceras in the Odenville and possibly in the Garden City Formation; M. primum, form the lower Cassinian part of the El Paso, is the oldest representative of the order Michelinoceratida so far recognized.

The family Troedssonellidae is revised to include Buttsoceras.

Part II:
The order Michelinoceratida is discussed, tracing the main evolution as previously known, making some new contributions, and pointing out problems which still remain. Previously proposed family names (exclusive of the Michelinoceratidae and Troedssonellidae discussed in the preceding work) are summarized, with some indication of their value and scope. A following section describes the families Proteocerati dae, describing the genera briefly and including some new ones; the new families Sphooceratidae, Engorthoceratidae, Offleyoceratidae are proposed, with new genera in some instances. A final section deals with contributions to the morphology of Orthoceros regularis, Pleurorthoceras clarkesvillense, and P. selkirkense, and Dawsonoceras.