Based on the preponderance of brachiopod evidence, the following new assignments are made: the upper part of the Gaptank Formation is placed in the Wolfcamp Series, as is the Skinner Ranch Formation. These assignments are based on early spasmodic arrival of such Permian elements as Limbella (an aulostegid brachiopod), Scacchinella (a well-known Permian type) and Waagenoconcha in rocks formerly considered of Late Pennsylvanian age. These three and other Permian types arrive in force in the famous Uddenites-bearing Shale Member of the Gaptank Formation, here placed at the bottom of the Permian. Many Pennsylvanian and Wolfcamp genera and the great biohermal assemblages of the Wolfcamp rocks had their heyday in the Skinner Ranch Formation, which represents the end of the Wolfcamp Series.

Faunas of the Road Canyon Formation have already been assigned to the Leonard Series by Cooper and Grant (1966) who regarded the preponderance of the fauna to be Leonard in generic content and general expression. Higher Word Formation assemblages are correlated with the Guadalupe type area as follows: China Tank Member fossils (formerly Second Limestone Member) appear in the Cherry Canyon Formation, Lower Getaway Limestone Member of the Cherry Canyon has the fauna of the Willis Ranch Member (Third Limestone of the Word of P. B. King) and Upper Getaway contains fossils of the Appel Ranch Member (Fourth Limestone of the Word). The South Wells Member of the Cherry Canyon, a black shale and carbonate facies, seems not to be represented in the Glass Mountains. Bell Canyon Formation (Hegler Member) fossils have been found in undolomitized limestone at the base of the Capitan Limestone in the Glass Mountains.

Although these changes are based largely on brachiopods they are in accordance with age indications of other groups in some cases, but not in all.

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