A fold in the surface epidermis composed of keratin[Kardong]. [ https://www.worldcat.org/search?q=bn%3A0073040584 http://en.wikipedia.org/wiki/Reptile_scale ]
Term information
Archosaurian (crocodilian and avian) scales and turtle scutes develop from local epithelial thickenings called placodes, though the scales of lizards and snakes (Lepidosauria) develop without placodes as skin folds (Maderson, '65; Sawyer, '72; Harris et al., 2002; Cherepanov, '89, 2006; Alibardi and Minelli, 2014; Moustakas- Verho et al., 2014; we do not consider crocodilian osteoderms, which have been called scutes by some workers, to be homologous to the skin appendages we discuss)[PMID:25877335]