The unusual silicified arthropods recovered from Miocene petrohferous nodules, described in this article, were collected by Gibron at U. S. Geological Survey Site #19057, the original discovery site of Dr. Allen M. Rassett, reported on by Dr. Allison R. Palmer (1957). This site is located in S.W 14 Section 24, R.I.E., T.IO.N., Calico Mountains, San Bernardino County, California, at 2420 feet altitude. We believe that this is the oldest fossil site yet reported on in this mountain range.
The specimens were all extracted from the nodules by use of hydrochloric acid by Gibron and Mrs. Gibron (Julia). Critical study has been made by Pierce, who also prepared the figures.