Pennsylvanian and Permian strata in the Whetstone Mountains are 4,700 feet thick and include, in ascending order, Black Prince, Horquilla, Earp, Colina, Epitaph, Scherrer, Concha and Rain Valley Formations. Early Pennsylvanian (Morrowan) fusulinids are present locally in Black Prince Limestone. Fusulinids are abundant in the lower and upper Horquilla Limestone and the lower Earp Formation. Those from the lower 450 feet of the Horquilla are of late Atokan and early Desmoinesian age; those from the upper 250 feet of the Horquilla are Missourian to early Virgilian; and those from the lower part of the Earp Formation middle to late Virgilian - the highest collection from the Earp may be early Permian. Fusulinids are present locally in the upper Concha Limestone and suggest an early Guadalupian age. Nine new species are described.