Figures 81, 82, and 83 of the 1887 volume Popular Zoology. Figure 81 depicts a barnacle (magnified) in the nauplius, i.e. first larval stage of development. Figure 82 depicts a trio of acorn barnacles. Figure 83. depicts a goose barnacle with one side of the shell removed, showing the enclosed soft parts.

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.