The book "On the Affinities of Leptarctus primus from the Collection of the Lady Museum of Natural History. Volume VI, Article VIII, pp. 229-331" was written by Jacob Lawson Wortman. In this work, the author investigates the affinities of the primitive bear cub Leptarctus primus, which lived in the late Oligocene. Wortman describes in detail the fossils and characteristics of this extinct species, and also makes comparisons with other representatives of the family. This book is a valuable source of information for paleontologists and anyone interested in the history of the development of mammals on our planet.