This text differs from the usual textbooks on comparative anatomy in that the subject is presented from the viewpoint of levels of being, a concept continually stressed by the late Dr. George Crile with whom the author was associated over a period of many years. The term levels of being as used here implies a stage of development of bodily systems reached by a group as expressed in performance and behavior.
Much of the factual information of this text has been gleaned from contributions of the past, but this has been supplemented by data gathered by the author in field trips and through the observation and dissection of many animals. Dispersed throughout the text are brief anecdotes of those expeditions, illustrating the relation of structure to function. This book is well printed, and the illustrations are excellent. The student of zoology should find it a stimulating text regardless of whether