The head skeleton of Amphisbaena alba Linnaeus

The skull of Amphisbaena alba Linneaus and its disarticulated components are described in detail and illustrated by photographs and labeled sketches. The cartilaginous components, particularly the adult chondrocranium are characterized in parallel. The bone formerly referred as the orbitosphenoid is considered as a distinct element nonhomologous to the synonymous element in other squamates and hence referred to as a "tabulosphenoid" (sphenoid plate). The element-X (of Zangerl) is considered to represent an epiphysis that facilitates the transmission of muscular forces to the growing skull, rather than being the remnant of an element no longer expressed. Cranial kinesis is discussed as are the general structural patterns associated with the relative distribution of spongy and dense laminar bone.