A deposit of phosphorite, estimated to be 11 feet thick, was found March 26, 1952, while the writer was mapping ancient sink fillings and collapse structures within the outcrop area of the Honeycut formation south of Marble Falls, Texas.

Sixty-eight species of trilobites, 10 species of inarticulate brachiopods, two species of articulate brachiopods, one ostracode and fragments of sponges, pelmatozoan echinoderms and unidentifiable organisms constitute the faunas of the Riley formation.

Wendel quadrangle is entirely within the Edwards Plateau province and is situated southwest of the Llano region.

Harper quadrangle is in the Edwards Plateau province south of the Llano region. The plateau surface within the quadrangle is dissected by the Pedernales River and its tributaries in the southern part, and by Threadgill and Edwards Creeks in the northern part.

Dry Branch quadrangle is in the Edwards Plateau province southwest of the Llano region.

The Tascotal Mesa quadrangle is in southeastern Presidio and southwestern Brewster counties, Trans Pecos Texas. Bandera Mesa and Tascotal Mesa are reached most easily from Marfa, 50 miles north, by the Marfa-Lajitas road which traverses the quadrangle from north to south.

The fossils described in this paper substantiate the Permian age of the Rustler formation. The Rustler fauna is largely molluscan and has a Whitehorse aspect.

Rocks of Cretaceous age crop out along the western margins of the deeper playa basins and along the southern and southeastern margins of the Llano Estacado.