Abstract

The purpose of this paper is to critically study and analyze all species belonging to the genus Pantosteus and to determine tbe validity of the characteristics that were used to separate the genus Notolepidomyzon from the genus Pantoateus. Special reference was made to the morphology of the fontanelle and the weberian ossicles. In order to more thoroughly comprehend the reasons for Cope describing Pantosteus as a new genus and Fowler describing Notolepidomyzon as a new sub-genus and then Snyder elevating it to the status of a genus as complete a historical sketch as possible was made using all literature known and available. A description has been made of the genus, the sub-genera, and all species concerned in this study. The two critical factors which separate the genus Notolepidomyzon from the genus Pantosteus received special attention. Illustrations showing the structure of the cranium have been made of representative specimens of all species except P. generosus. The fontanelle remained constant in some species, but in others it varied greatly. The weberian ossicles vere studied and illustrations made or species within both genera. No definite critical factor could be found with the ossicles that could be used to separate the genera. It is the proposal of the writer that since the characteristics that were used to distinguish these two genera are not consistent nor completely reliable, the genus Notolepidomyzon not be recognized as separate genus, but retained as a sub-genus distinguished from the sub-genus Pantosteus primarily on the thickness of the cranium and the open or obliterated fontanelle. The material and evidence needed to support this proposal is contained in this paper.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

Rights

http://lib.byu.edu/about/copyright/