Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/5



is not designed in the present essay, to give descriptions of the known remains of the Batrachia, Reptiles and Birds, which have been more or less fully made known by others. This is left for the day when our knowledge shall more nearly approach completeness. While the subject is in its infancy, I have thought best to describe only those species and types which are new, and those portions of imperfectly known forms which will throw additional light on their relations and affinities. In adhering to this plan, I have been able to add no little to the history of the Reptiles already described by my predecessors, Leidy, Owen, Dawson, Wyman, Lea, etc. Where, however, I have had nothing to add, I have referred to their published descriptions, which are numerous and well-known. The literature of the subject will then be found under the respective specific heads.

The present Memoir was originally prepared under the title of "Contributions to the History of the Vertebrates of the Mesozoic Periods in New Jersey and Pennsylvania," and presented to the Academy of Natural Sciences of Philadelphia, for publication, Fifth Month, 14, 1867. The more important parts of its contents were at the same time embodied in a series of remarks before the Academy. This essay was withdrawn, owing to delay in the publication, and the remarks made were not printed. An abstract of part