Seven osteological characters of the axial skeleton are studied in the eight species of the genus Pampus. The characters include: pattern of interdigitation of the dorsal- and anal-fin pterygiophores with the neural and haemal spines of the vertebrae, structure of the vertebral column, distribution of the dorsal- and ventral- procurrent caudal-fin rays, distribution of the principal caudal-fin rays and the morphology of the caudal-fin skeleton. All these features appear to be useful in the characterization of the eight species of the genus Pampus. Formulae for the structure of the vertebral column, the dorsal- and anal-fin pterygiophores’ interdigitation with the neural and haemal spines of the vertebrae, distribution of the dorsal and ventral procurrent caudal-fin rays, and distribution of the principal caudal-fin rays were developed. Pampus nozawae was recently considered a synonym of P. argenteus. However, according to the characters used in the present study, this species is notably distinct from P. argenteus.

The gross osseous anatomy of the spine has been the subject of much study but the internal architecture and trabecular anatomy of thoracolumbar vertebrate has not previously been well described. This study is based on high resolution x-ray images of 56 isolated thoracolumbar vertebrae and thick sections obtained from them. A previously undescribed array of trabeculae was documented which originated from the medial corner of the base of the pedicles and extended in a radial array throughout the vertebral body. This trabecular array persisted even in severely osteoporotic specimens. The cortex of the vertebral canal thinned abruptly near the base of the pedicle creating what may be a stress concentration at this site. This corresponded to the site of origin of the trabecular array. The presence of this possible stress concentration, in proximity to the trabecular array, may provide an explanation for the trapezoidal shape of the bony fragments that are frequently retropulsed into the spinal canal in axial load type burst fractures, common in this area of the spine.

In this paper we examine metamerism in the vertebral column of certain mammals from the perspectives of development and adaptation. To this end we examine the patterns of metameric variation of dimensions of the neural (vertebral) canal, vertebral body and spinous process in man and inbred strains of mice. The data from inbred strains of mice indicate that variability in dimensions within a strain reflects the temporal ordering and nature of developmental influences on vertebral morphogenesis. Differences between strains parallel the within-strain findings. These findings are attributed to somatic and neural influences on morphogenesis. Comparisons between mice and man indicate that these same influences can be invoked to explain and interpret the mosaic nature of vertebral column evolution. These findings lead us to conclude that different vertebral elements and levels are subject to different interactions of evolutionary and morphogenetic influences. The study of these influences and their interactions should prove fruitful in developing an understanding of the relationship between adaptation, development, growth and function in the skeleton generally.