Cephalic Index
Cephalic Index, basic measure of the shape of the skull , used by scientists of the 19th and early 20th centuries in classifying humans. Devised by Swedish anatomist Anders Retzius in the 1840s, the cephalic (or cranial) index expresses the width of the skull as a percentage of the length from front to back. Craniologists distinguished three basic classifications of skulls based on the cephalic index: dolichocephalic (long skulls), with widths of less than 75 percent of the length; mesocephalic (medium skulls), with indexes of 75 to 80; and brachycephalic (broad skulls), with indexes of more than 80 percent.