摘要："Microstructure of the outer shell layer of Upper Paleozoic pectinoid bivalves usually, but not always, is strikingly different in right and left valves, and the differences characterize groups at the generic and familial levels, serving to augment sparse morphologic characters available for taxonomic and phylogenetic studies. The progress note given here is one aspect of an ongoing comprehensive taxonomic survey of Permian and Lower Triassic Pectinacea"--P. [1].
