Figures 475 and 476 of the 1887 volume Popular Zoology. Figure 475 depicts a siamang, an arboreal black-furred gibbon native to the forests of Indonesia, Malaysia and Thailand. Figure 476 depicts a gibbon as described by American zoologist and taxidermist William Temple Hornaday (1854-1937).

Designed to give students an understanding of the animal worlds, Popular Zoology describes and identifies the animals in two kingdoms of nature: the Invertebrates and the Vertebrates. The volume includes copious intaglio printed illustrations of the animals described, as well as a series of charts detailing the systematic arrangement of representative forms. This is one of a series of textbooks written by American educator Joel Dorman Steele (1836-1886), who often worked in collaboration with his wife Esther Baker Steele (1835-1911). Subjects addressed in a similar manner in other volumes include chemistry, human physiology, physics,and astronomy. Popular Zoology was completed posthumously by J. W. P. Jenks (1819-1894), Professor of Agricultural Zoology at Brown University, who is credited as a co-author on the volume.