This part B of the fourth volume of The Crustacea contains chapters on: ● Crustaceans in the Biosphere ● Crustaceans and Mankind ● Crustaceans in Art ● Orders Lophogastrida, Stygiomysida, and Mysida [collectively known as Mysidacea] As evident from the number 4B tagged to this volume, vol. 4 as originally planned had to be split into two fascicles, 4A and 4B, simply because of the numbers of pages covered by the various contributions meant for volume 4. The chapters in this book grew out of those in the French edition volumes 7(II) and 7(III)(A). Overall, this constitutes the seventh tome published in this English series, viz., preceded by volumes 1 (2004), 2 (2006), 9A (2010), 9B (2012), 3 (2012), and 4A (2013). Readers/users should note that from vol. 4A onward we have had to abandon publishing the chapters in the serial sequence as originally envisaged by the late Prof. J. Forest, because the various contributions, i.e., both the updates and the entirely new chapters, have become available in a more or less random order.