Fig. (11) Lepidosaurs. Ventral views of brain vessels of A) tuatara (Sphenodon punctatus) modified from Dendy [80], B) desert monitor lizard (Varanus griseus) modified from Corti [106] and C) Sonoran lyresnake (Trimorphodon lambda) modified from Gillilan [82] showing variation within lepidosaurs in the branching pattern of CCA into ACC, PCC and Mes divisions. In all three, the PCC fuse to form a midline, unpaired basilar artery (BA) that gives off transverse branches and joins the first spinal artery (1^st SA) at the spino-medullary junction. Cranial nerve roots are indicated by Roman numerals. Oph, connection of ACC with ophthalmic artery; Pit, pituitary branches.