作者：叶祥奎

摘要：The emydids and testudinids are two common and main groups of cryptodire turtles. We meet them usually in Cenozoic deposits and recent. In fossils, as other turtles, they represent generally by their shells only. Though the typical species of testudinids can easily be recognized by their structures of neural, costal and epiplastral plates, etc.; it is still somewhat difficult to distinguish some testudinids, which are not so typical, from emydids by shells. A general remark of some structural similarities and differences of the shell of these groups, especially the bony plates of them, is presented.
    In the second section of the present paper, the origin and the flourish and decline of these two groups are talked. It seems reasonable to believe that the emydids and testudinids originated respectively from early Cryptodira, and developed in Cenozoic as two different branches, one adapted chiefly in fresh-water and another on land. It is, therefore, somewhat better to consider them as two groups (Families or Subfamilies) rather than to gathered them as one.
    At last, a list of species of emydids and testudinids known in China is arranged through geological time. Since the occurrences of Paleocene emydids known recently in China, as we have seen in the list, the earliest record of this ehelonian group is thus more certain.

卷期：20卷 01期

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