Planolites and Skolithos from the Upper Precambrian-Lower Cambrian, White-Inyo Mountains, California

Eight species of the trace fossil Planolites Nicholson, 1873, unbranched horizontal burrows, and two species of Skolithos Haldeman, 1840, unbranched vertical burrows, occur in the Upper Precambrian and Lower Cambrian rocks of the White-Inyo Mountains, California. Two species, P. rcticulatus and S. bulbus, are new. The genus Planolites and its relation to Palaeophycus Hall, 1847, is reviewed. The presence of true branching is suggested as the criterion for distinguishing Palaeophycus from Planolites. All the named species of Planolites and Palaeophycus are listed.