Our database contains three appendices: 250 photographs of living mammals included in several representative specimens, four caliper measurements for each specimen, and complete skull images with the mandible for the primate pages. Most of the photographs come from zoos. A few photos of the monkeys and apes were obtained by courtesy of researchers in primatology. Nasion-basion length, zygomatic breadth, posterior cranial breadth (width of braincase esp. neurocranium), and maximum length (prosthion-opisthocranion length) of all specimens were measured with calipers; however, the data sometimes are missing due to unidentifiable points. Zygomatic Breadth in our measurement is defined as the width of the cranium around the zygomatic region, which usually is obtained by measuring bizygomatic width, but sometimes by measuring biorbital width if larger. On the pages of representative primate specimens, images of the cranium with the mandible in frontal and lateral views are presented, which were originally photographed for the Visual Database of Primatology (http://www.pri.kyoto-u.ac.jp/gazodb/honemenu.shtml).