The Devonian-Mississippian transition outcrops of central Texas are here described summarily and assigned to a new stratigraphic unit, the Houy Formation. The beds included are mainly Upper Devonian, but partly Lower Mississippian. Locally a basal fraction may be Middle Devonian.

Fall Prong quadrangle is in the marginal portion of the Edwards Plateau near the southeastern corner of the Llano region. Almost three-quarters of the quadrangle is within the Edwards Plateau, and the rest consists of valleys of the Llano basin cutting back into the plateau.

The lead and zinc deposits in the Upper Cambrian rocks of central Texas are reviewed in the light of new detailed information. Included are analytical data for all deposits, detailed stratigraphic sections of the Cambrian rocks, and maps at a scale of 4 inches to the mile.

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.

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.

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