Measurements of the skull and of some of the long bones of the muskrat (Ondatra zibethicus cinnamominus)

Abstract The skull, mandible, and five pairs of long bones from the skeletons of 125 muskrats were weighed and measured. Each bone of the pairs of long bones was weighed and measured separately. Thirteen dimensions of the skull were determined. The long bones are slightly less variable in length than the skull dimensions. There is a rather wide range of variation in the thirteen dimensions of the skull, with the length and breadth of the skull less variable than the lengths of the long bones. The coefficients of correlation show that the weight of the skull is a good index to the weights of the long bones. The skull length has likewise high correlations with the lengths of the long bones and the longitudinal dimensions of the skull, with the exception of the palatine slits. The transverse diameters are not significantly correlated with the skull length. The long bones are asymmetrical in weight and length. They are longer more frequently on the left side and all except the tibia are heavier more frequently on the left side.