The lateral superior olivary nucleus in 37 species of mammals was drawn with a Zeiss drawing tube from protargol-silver stained material. The pattern of laminar infolding generally conformed to the S-shaped and U-shaped convolutional patterns described by Hoffman (1908). In species with a relatively large cell number and a relative small cross-sectional area, there tends to be substantial laminar infolding within the convolutional pattern. Two independent estimates of the amount of laminar infolding were made and contrasted with the number of segments in the general convolutional pattern. Neither amount of laminar infolding nor number of convolutional segments was found to correlate with number of cochlear turns. However, in species in which the laminar pattern is well defined, the convolutional pattern and amount of laminar infolding appear to conform well to the sensitivity range and area of greatest sensitivity as seen in behavioral audiograms for the species.