The present study was undertaken in order to provide information upon the normal skeletal structure of bluegill sunfish, Lepomis macrochirus RAFINESQUE, to the researchers using it as an experimental animal and to the taxonomists trying to work out the relationship between the members of the Centrarchidae family.
This study is based upon the examination of 100 bluegill specimens made by cleaning, staining, and roentgnography. The observations can be summarized as follows:
i) Statistical analyses of various skeletal proportions revealed small fluctuations except for the cranium height and width which were observed to be size-dependent.
ii) Correlation between external and skeletal characters have been made to predict the position of several skeletal components on the body of fish without subjecting it to the troubles of scissors and forceps.
iii) Basic scheme of the arrangement of bones except for their shapes and sizes, has been found out to be more or less the same as that of Sacramento perch studied by DINEEN and STOKELY (1956). However, reduction in the number of certain skeletal components has been observed in bluegill.
iv) A second uroneural has been discovered in bluegill which hither-to had not been reported from any other centrarchid including bluegill.
v) Comparison of meristic measurements as stated by various authors presented some difference in the number of dorsal soft ray, trunk vertebrae, scales, and gill rakers.