go to at least fifty historians and evolutionary biologists who responded in various ways to such open-ended inquiries as ". . . and what do you think about neoteny?"; to those who read parts of the manuscript and added their insights to this collective effort: Polly Winsor, David Kohn, Fred Churchill, Dov Ospovat, Joan Cadden, David Jablonski, my class in the history of embryology, and many others; to those who brought me references to recapitulation from their newspapers and novels; and, above all, to an institution that has its own humanity and seems to me more an organism than a place—the Library of the Marine Biological Laboratory at Woods Hole. Where else could an idiosyncratic worker like me find a library open all the time, free from the rules and bureaucracy that stifle scholarship and "protect" books only by guarding them from use. It is an anomaly in a suspicious and anonymous age. May it survive as it is, despite all the improbabilities. I finished this book in Gar Allen's house on Hyatt Road in Woods Hole, appropriately named after the man who first identified clearly the role of developmental timing in heterochrony—the major theme of this book (a meaningless coincidence, but I thought I'd mention it). I thank the American Philosophical Society for supporting my work in English libraries.

I don't know why authors feel constrained to say so—for it should be obvious—but I too hold all these dear friends and colleagues free, blameless, unencumbered, and innocent of responsibility for the errors in this book. How could it be otherwise; it is, after all, my work. I am responsible for all translations from non-English languages (except those few quoted from a secondary, English source). Finally, my thanks to G. G. Simpson for his intellectual breadth and for his ability to inspire a ten-year-old boy with his general writing, thereby eclipsing a previous worship of Joe DiMaggio. To my wife, Deborah, for being the kind of person about whom one could never write the conventional: "Thanks to my wife, whose patient understanding . . . and who typed the manuscript and kept the kids out of my hair." And to my parents for unflagging enthusiasm and encouragement, in the absence of any tradition for advanced education in our family, and against the bemusement of some older relatives who didn't know what paleontology meant and who, upon finding out, could only mumble (with an inflection that I cannot transcribe on paper): "That's a profession for a Jewish boy?"