Memoir 7

By R. H. Flower, 1961.

Text Section

229 pp., 10 figs.

Plate Section

124 pp., 52 plates.

Twenty-seven species are described from the Montoya Group of New Mexico; 17 from the Second Value Formation; 6 from the Aleman, and 5 from the Cutter; 1 species being common to the Aleman and the Cutter. Only four species have been described previously; the others are new. Four species are not determined specifically. One Aleman species is tentatively identified in the Cutter; others are distinct for the three formations. Two new genera, Crenulites and Trabeculites, are described. Species from other regions described and discussed, and in some cases revised, include five species of Favistina, Protrochiscolithus magnus, and Saffordophyllum crenulatum, three of Crenulites, one of Trabeculites, and two assigned to Foerstephyllum.

Regional analysis strengthens the Red River affinities of the Second Value Formation and the Richmond equivalence of the Aleman and Cutter Formations, but fuller evaluation must await more precise study of corals of other Ordovician faunas, particularly in western and northern North America.

Revised concepts of morphology and relationship are required, notably the derivation of septa as secondary structures from a primitive wall, and the primitive nature of a simple fibrous wall from which are derived trabecular walls on the one hand, and walls with an axial plate on the other, the axial plate developing both into the primary wall of the higher Favositidae, and into the epitheca of the rugosan types. The present study fails completely to support division of these corals into Tabulata and Rugosa, but it is felt that alternate proposals would be premature. A new structure, poikiloplasm, is described, which may line carallites, be concentrated as spherical knobs, with or without a thin connection, or form groups of discrete spheres.

A summary is appended, briefly summarizing characters by which the Montoya species can be differentiated readily.