Sodium metatungstate (SMT), 3Na2WO4 · 9WO3 · H2O, is a nontoxic (Sax, 1979), high-density (1.00-3.10 g/cm3) separating compound which results in nearly neutral (pH 6) solutions of relatively low viscosity. It was presented as a medium for density gradient centrifugation by Plewinsky and Kamp (1984). Since then, investigators have used SMT (or sodium polytungstate) as a high-density medium for routine mineral separations, for recovery of conodonts from insoluble residues, for separation of various feldspar species from one another, and for segregation of inorganic mineral fractions (ash) from coal.

In the past few years the Cleveland Museum of Natural History has received several inquiries as to our source of dolomite for use with S.S. White® industrial airbrasive units. We have been using inexpensive, “agricultural” dolomite with these units for several years. This source was “discovered” by testing of a wide variety of dolomite sources by Peter Kotulak, a former preparator at the Museum, under the direction of M.E.W. We are currently using OHSO® Pulverized Limestone, a kiln-dried dolomitic limestone recommended for agricultural, and lawn and garden, use. It is produced by the Ohio® Lime Co., of Woodville, Ohio. A 22.7 kg (50 pound) bag costs $2.25, and is available at building supply companies. The dolomite must be sieved and dried to prevent clogging of the unit's line and nozzle. We use a Ro-Tap® Testing Sieve Shaker to sieve the material, with #30 (595 micron), #60 (250 micron), and #100 (150 micron) U.S.A. standard testing sieves. An incandescent desk lamp can be placed over an open container of the sieved dolomite to keep it dry. Used powder may be re-sieved for reuse if desired.

Olson (1970) erected the genus Goniorhynchus for a Lower Permian microsaur amphibian from Oklahoma. Carroll and Gaskill (1978) used this genus as the type of a new family, Goniorhynchidae. Schultze and Foreman (1981) noted that the name Goniorhynchus Olson, 1970, was preoccupied by Goniorhynchus Hampson, 1896, and they proposed the replacement name Rhynchonkos; however, they retained the family name as Goniorhynchidae.