Morphometric Variation and Function in the Baculum, with Comments on Correlation of Parts

Probable functions of the baculum are reviewed. Consideration of vectors of resistance of the vaginal orifice and of forces of the baculum reveals possible reasons for the specialization of the bacular tip in some carnivores and rodents. Coefficients of variation of length and some other measurements of some bacula of adult mammals are compared, and measures for Procyon and Rattus are correlated. Variations of length of baculum and width of tip are often exceeded by other bacular variations. The length is usually less variable than its components; this pattern of variation can be explained in part by (1) lack of correlation of the subsidiary measures, and (2) algebraic considerations. The ossicles of complex bacula show an increase in variation distally. The influence of sex on the baculum, and the function, form, and variation of the os clitoridis in several kinds of mammals are discussed.