The form and gross relations of the dugong's skeletal muscles are described, illustrated, and compared with published descriptions of manatee muscles. Maps of muscle attachments to the bones and data on skin thickness are included.Though closely paralleling cetaceans in swimming adaptations, sirenians are much less specialized in this regard, since they are not active predators. Manatees show less anatomical specialization and presumably less efficiency and endurance in swimming than dugongs because manatees are less active and inhabit more protected waters. The structure of the shoulder region is quite different in the two sirenian families and may reflect the requirements of maneuvering in more or less open habitat. Other muscle systems, however, are not notably different in the two families
