Memoir 22—Part I-Some El Paso Guide Fossils; Part II-Fossils from the Smith Basin Limestone of the Fort Ann Region; Part III-Fossils from the Fort Ann Formation; Part IV-Merostomes from the Cassinian Protion of the El Paso Group

By R. H. Flower, 1969, 63 pp., 1 table, 9 plates, 1 index.

Fossils from the El Paso Group are here figured and described, largely species diagnostic of some horizons or of correlative significance. The forms are listed in the Table of Contents. Here are brought together illustrations and descriptions of some fossils from the El Paso Group of NM and western Texas. They are largely forms which characterize several of the formations or are of correlative significance. The selection is far from being representative. No attempt is made to treat the calcareous algae, abundant and massive at several horizons. As yet these fossils have not yielded taxonomically in such a way that those of the various horizons can be distinguished.

Cephalopods, particularly the endoceroids, supply associations which characterize three main and several minor horizons. The Endoceratida are being treated in a separate work, which has now grown to somewhere around 40 plates and a bale of manuscript, and it seems unwise to duplicate any of this work here. The endoceroids supply the main faunal criteria for the recognition of the faunas of the Cooks, the Victorio Hills, and the McKelligon Formations. Another work in an advanced stage includes the Tarphyceratida, the exogastric cyrtocones and nautilicones, also of considerable faunal significance though less generally abundant. Ellesmeroceratida of the El Paso Group were included in a revision of the order already published. Some new forms have since come to light.

Sponges are abundant in several horizons from the Cooks Formation to the top of the El Paso Group; they are particularly characteristic of stromatolitic facies where slender endoceroids and the more rapidly expanding piloceroids are also abundant. The El Paso materials have been entrusted to Dr. Keith Rigby for description, and they promise to yield information of faunal and stratigraphic value. The author was tempted to figure some of these, but was unable to find some of the negatives, and the best specimens were on loan.

The residue from which selected forms are described, is a heterogeneous lot. A number of the species which characterize several horizons, have been in manuscript for some years, and some have been mentioned, though only broadly identified, in summaries of the El Paso, largely prepared by requests for various guidebooks. Delay was caused in part by taxonomic problems in groups of which the writer's knowledge is far from intimate, and in part by the constant hope of obtaining additional and better material.