Chancelloriia Walcott, 1920 y Reticulosa Reid, 1958 del Cámbrico medio de San José de Gracia, Sonora, México.

Isolated sclerites of Chancelloria eros Walcott, 1920, Diagoniella sp. and associations of stauractine-hexactinellid and hexactinepentactine spicules are described for the middle Cambrian of San José de Gracia, Sonora, Mexico; the material proceeds from a shelf marine sedimentary sequence, consisting mainly of shale interbedded with limestone, in association with fossils representatives of the Biozone Albertella, like Peronopsis bonnerensis Resser, 1938; Oryctocephalites walcotti Reeser, 1938; Elrathina antiqua Palmer and Halley, 1979, Ogygopsis typicalis Resser, 1939, and inarticulate brachiopods. Chancelloria eros Walcott, 1920 has been previously reported for middle Cambrian in Arrojos Formation, in the state of Sonora, Mexico, and Chancelloria sp. from the early Cambrian in Puerto Blanco Formation, in association with ?Kiwetinokia in Cerro Rajon in Caborca region, being this the first record for San Jose de Gracia, central Sonora. [ABSTRACT FROM AUTHOR]