 Above the rectum tract a large area of horizontal unsegmented muscle fibres is present, probably representing the unsegmented "Musculus caudofemoralis longus" of the tail base, the main retractor muscle operating on the thighbone.These fibres are polygonal in cross-section and show the intercellular spaces also.Below some tail base vertebrae the connective ligaments between the chevrons are present, forming the "ligmamentum interhaemale", but also some small muscle fibres and some mysterious hollow tubes arranged in a herringbone pattern; the latter perhaps represent the myosepta of the myotomes, the segments of the "Musculus iliocaudalis" or the "Musculus ischiocaudalis".