Transactions and proceedings and report of the Philosophical Society of Adelaide, South Australia . rior valve is practically without sculpture,with the exception of the very fine decussate pattern thatcovers the whole shell, probably due to the megalopores. Comparisons.—While at first sight this shell, with itspolished ivory-like appearance, seems very different from , Pils., its method of sculpture approaches that ribs in the pleural area are less raised and further apartthan is the case in that species, and suggest weather-boardingrather than the narrow well-raised rib
Transactions and proceedings and report of the Philosophical Society of Adelaide, South Australia . rior valve is practically without sculpture,with the exception of the very fine decussate pattern thatcovers the whole shell, probably due to the megalopores. Comparisons.—While at first sight this shell, with itspolished ivory-like appearance, seems very different from , Pils., its method of sculpture approaches that ribs in the pleural area are less raised and further apartthan is the case in that species, and suggest weather-boardingrather than the narrow well-raised ribs, separated bv deepgrooves of R. tricostalis. The lateral areas are divided intotwo ribs, instead of three, and the nodules are more roundedand flatter. The scales, both in shape and lack of grooving,are of a different character. R. verconis, Torr and Ashby,which is somewhat kindred in sculpture, has erect, pointedscales, of the same type as R. jacksonensis, Ashby. Then,again, the habit of this species in adhering to the underside oflimestone rocks buried deeply in sand is very distinct from. bO
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1878
