摘要：

A detailed analysis is made of all the named Triassic, Jurassic and Cretaceous genera belongingto the order Rhynchonellida of the Phylum Brachiopoda. The classification is entirely revised and evolutionary lineages traced for each division, using all the available information on external and internal characters of the fossil shells. It is demonstrated that the present state of knowledge is such that most of these lineages are now more or less completely known, though in a few cases there are astonishingly long gaps in the record of particular stocks. Several lineages can be traced through from the Palaeozoic and others can be traced on into the Caenozoic, but certain groups have no obvious ancestors or descendants. A few evolutionary trends can be recognised, mostly at specific level, but the general evolutionary pattern seems to be one of successive «take-overs of the more favourable environments by different stocks. Conservative stocks persist in the less popular habitats.

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