fossil Amphibia were mistaken for reptiles, as indicated by the frequent termination '-saurus' in their names.
The nearest living representative of these extinct Proreptilia is the New Zealand reptile Hatteria, or Sphenodon, close relations of which are known from the Upper Trias; while others—e.g., Palæohatteria—have been discovered in the Permian. Anyhow, Sphenodon is the reptile which stands nearest to the main stem of our ancestry.
The most important characteristics of the Reptilia, which mark a higher stage or level, are (1) The entire suppression of the gills—although during the embryonic development the gill-clefts still appear in all reptiles, birds, and mammals; (2) The development of an amnion and an allantois, both for the embryonic life only, but so characteristic that all these animals are comprised under the name of Amniota; (3) The articulation of the skull with the first neck vertebræ by well-developed condyles, either single (really triple) or
