Some middle Cambrian agnostoids from the Precordillera Argentina.

Resumen

Agnostoid trilobites are described from Middle Cambrian sediments in the Precordillera of Mendoza and San Juan provinces. The following taxa occur at Solitario Hill, Mendoza: Clavagnostus canotensis, Tomagnostella exsculpta, Agnostus exsulatus, Agnoslus? sp., Oedorhachis australis, Ptychagnostus aculeatus and Ammagnostus sp. Taxa from the Ojos de Agua locality in San Juan comprise: Kormagnoslus seclusus, Peronopsis tenuis and Ballagnostus? sp. There are the first agnostoids recorded from the San Juan area. Ptychagnostus aculeatus from Mendoza is here recorded for the first time in Argentina. A late Middle Cambrian age is assigned to the strata containing the assemblages of both Mendoza and San Juan.