PLESIOMEGALASPIS Thoral, 1946. Plesiomegalaspis planilimbata A n ge l i n, L. Ordovician, Hun neb erg, Vastergotland, Sweden (x2.9). (SMNH No. Ar 14405, photographed by the author at SMNH, through courtesy of Jan Bergstrom.)

ISOTELUS De Kay, 1824. Isotelus gigas D e Kay (x2.9). Trenton group, M. Ordovician, Trenton Falls, New York (UCWM, loaned by FMNH.) Specimen whitened with magnesium oxide. Since the original specimen is shiny black against a black matrix, the uncoated sample would be exttemely difficult to portray.

hotelus maximus Locke, U. Ordovician, Cincinnati, Ohio (x0.85). This trilobite, Ohio State Fossil, could reach impressive size, in excess of thirty centimeters in length. This specimen is particularly well preserved. (Collected by Dan L. Coopet, photogtaphed by the author, through courtesy of David C. Rilling).

HOMOTELUS Raymond, 1925. Homotelus bromidcnsis

Esker (x3. 1). Bromide Formation (Poolville member), M. Ordovician, Blackriverian, Criner Hills, Carter County, Oklahoma. (RLS coll., now at FMNH.)

Homotelus bromidensis Esker, as in plate 133 (xl.35). This exceptional group of adult, whole individuals may represent a mating assemblage. (Photographed by the author, through courtesy of David C. Rilling.)

PSEUDOGYGITES Kobayashi, 1934. Pseudogygites latimargnatus

(Hall), Lower Whitby Formation, U. Ordovician, Bowmanville, Ontario, Canada (x3.2). Relatively minot differences distinguish this younger trilobite from Ogyginus, but the similarity of these two taxa is thought to be the tesult of parallel evolution, rather than direct relationship. Specimen whitened with magnesium oxide. (RLS coll., id.)

Pseudogygites latimarginatus (Hall), same origin as for the preceding plate (xl.3). In this attractive assemblage, the trilobites are naturally coated by a whitish patina, possibly part of the calcified exoskeleton. Print from color negative. (Photographed by the author, through courtesy of Michael Thomas.)


Ogygiocaridinae Raymond, 1937

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