Brigham Young University Science Bulletin, Biological Series


The complete skeletal anatomy of Pituophis catenifer deserticola Stejneger is described in detail. The osteology of this species is compared with that of Thamnophis radix haydeni Kennicott in the following areas: atlas, axis, first thoracic, other thoracic lumbar, anterior caudal, middle caudal, and posterior caudal vertebrae, as well as the skull and hyoid apparatus.

Many structural similarities exist in these two species of colubrids. The more important structures or aspects in which similarities were observed are: (1) the natural division of the vertebral column into regions and subregions, (2) the gross morphology of the various types of vertebrae, (3) the number and types of bones comprising the skull, (4) the number and location of the majority of vertebral and skull foramina, (5) the structure of the hyoid apparatus and the ribs, and (6) the position and shape of the stapes.

The major structures or aspects in which there are differences encountered between the two species are: (1) the shape of the anterior hypapophysis of the atlas, (2) the existence or lack of metapophyses on the first thoracic vertebra, (3) the presence or absence of hypapophyses on the lumbar vertebrae, (4) the relative size and shape of the lymphapophyses, (5) the structure of the caudal haemapophyses, (6) the number of vertebrae in each region and subregion, (7) the relative size and shape of the cranium and its component bones, (8) the shape and character of the septomaxillary process, (9) the existence of lack of paired parietal foramina, (10) the shape and extent of the postorbitals, (11) the presence or absence of basioccipital hypapophyses, (12) the number of maxillary, pterygoid, and mandibular teeth, (13) the relative size and character of the supratemporal, quadrate, and mandible, and (14) the relative size of the hyoid apparatus.