680 



ACKNOWLEDGMENTS 



248 

 250 

 251 

 254 

 255 

 260 

 261 

 163 

 264 



11-47, 

 11-50, 

 11-51, 

 12-3, 

 12-5, 

 12-10, 

 12-11, 

 12-13, 

 12-14, 

 12-15, 265 

 12-19, 267 

 12-22, 270 

 12-25, 274 

 12-27, 275 

 13-3, 281 

 13-4, 282 

 13-7, 285 

 13-9, 287 



13-11, 289 

 13-12, 289 



13-13, 290 

 13-14, 291 

 13-15, 292 



13-16, 292 

 13-18, 294 



13-19, 295 

 13-20, 296 



13-24, 300 

 13-25, 300 

 13-26, 300 

 13-27, 301 

 13-39, 319 

 13-41, 321 

 13-42, 322 



13-44, 325 

 13-46, 327 

 13-52, 332 

 13-54, 335 

 13-58, 340 

 13-59, 341 



13-60, 341 

 13-61, 342 



13-62, 343 

 13-63, 344 

 13-64, 345 

 13-66, 347 

 13-67, 348 

 13-68, 350 

 13-69, 351 

 13-70, 352 

 13-71, 352 

 13-72, 353 

 13-73, 354 

 13-74, 356 



G. H. Needham 

 New York Zoological Society 

 Specimen furnished by Bert Johnson 

 Redrawn in part from Storer 

 Based on Haas 

 Based on Lefevre and Curtis 

 George Lower 

 Courtesy of Lewis Batts 

 Woody Williams 

 Woody Williams 

 Woody Williams 

 George Lower 



Adapted from Delage and Herouard 

 George Lower 

 George Lower 

 From various sources 

 Woody Williams 



Courtesy of William Cristinelli, Mich- 

 igan Department of Conservation 

 Upper, modified from Goodrich 

 Upper, redrawn from Romer after 

 Traquair 



Adapted in part from Wiedersheim 

 George Lower 



Courtesy of William Cristinelli, Mich- 

 igan Department of Conservation 

 Woody Williams 



The Sport and General Press Agency, 

 Inc., London 

 Adapted from Dean 

 Specimens furnished by Paul A. 

 Wright 



Courtesy of Lewis Batts 

 Courtesy of David Delzell 

 Courtesy of David Delzell 

 Courtesy of David Delzell 

 Adapted from Rugh 

 Adapted from Colbert 

 Courtesy of Claude Hibbard, Uni- 

 versity of Michigan Museum of Zool- 

 ogy 

 Courtesy of Detroit Zoo 



Arthur Center 

 Courtesy of Lewis Batts 

 Courtesy of Detroit Zoo 

 New York Zoological Society 

 Upper, courtesy of the General Bio- 

 logical Supply House; Icwer, Woody 

 Williams 



Courtesy of Lewis Batts 

 Upper, courtesy of William Burt; 

 lower, courtesy of Detroit Zoo 

 Courtesy of William Burt 

 Courtesy of Detroit Zoo 

 Courtesy of Detroit Zoo 

 Woody Williams 

 Adapted from Romer 

 New York Zoological Society 

 New York Zoological Society 

 New York Zoological Society 

 New York Zoological Society 

 New York Zoological Society 

 New York Zoological Society 

 Adapted from Osborn 



14-3, 370 

 14-4, 371 



16-2, 395 



16-19, 420 

 16-26, 431 

 16-27, 431 

 16-28, 432 

 16-30, 438 



16-32, 440 

 16-33, 444 



16-34, 446 

 16-35, 447 



16-36, 448 



17-6, 459 

 17-10, 466 

 19-2, 492 



19-6, 496 

 21-3, 533 

 21-5, 537 

 21-10, 543 



21-13, 546 



23-7, 568 

 23-9, 571 

 23-10, 572 

 23-11, 572 

 23-12, 573 



23-13, 574 

 23-14, 576 

 23-15, 577 

 23-17, 579 

 23-18, 579 

 24-1, 

 24-4, 

 24-11, 

 24-17, 



582 

 585 

 599 

 610 

 24-20, 614 



24-21, 617 

 25-1, 625 



25-2, 626 



Redrawn with modifications from 

 Neal and Rand 



Upper, redrawn with modifications 

 from Neal and Rand; lower, courtesy 

 of the General Biological Supply 

 House 



Redrawn with modifications after 

 Kahn 



Partly after Arey 

 Woody Williams 

 Courtesy of Paul A. Wright 

 George Lower 



Specimens supplied by Paul A. 

 Wright 



From various sources 

 Courtesy of Hans Selye, Textbook of 

 Endocrinologij, Acta, Inc. 

 From various sources 

 Courtesy of Hans Selye, Textbook of 

 Endocrinologij, Acta, Inc. 

 Courtesy of Hans Selye, Textbook of 

 Endocrinology, Acta, Inc. 

 After Kabanov from Moment 

 Adapted from Kahn 

 Redrawn in part after Carlson and 

 Johnson 



From various sources 

 George Lower 

 George Lower 



Courtesy of C. G. Reather, Depart- 

 ment of Embryology, Carnegie Insti- 

 tution of Washington 

 Models from Cleveland Health Clinic, 

 University of Michigan Museum of 

 Zoology 



Adapted from Avey 

 Redrawn in part from Etkin 

 Redrawn after Spemann 

 Redrawn after Spemann 

 Courtesy of William Crestinelli, 

 Michigan Bureau of Fisheries 

 Redrawn after Spemann 

 Redrawn after Barth 

 Redrawn after Barth 

 Redrawn after Patten 

 Redrawn from Patten after Shammes 

 Courtesy of Central Scientific Co. 

 Modified from Emmens 

 Redrawn after Etkin 

 Redrawn after Etkin 

 Upper, courtesy of P. Fogh-Ander- 

 sen; lower, courtesy of Arne Birch- 

 Jensen; both of the University Insti- 

 tute for Human Genetics, Copen- 

 hagen, Denmark 



Percentages taken from Cyril Burt, 

 Intelligence and Fertility, Eugenics 

 Society (London, 1946) 

 Age estimates from Simpson, The 

 Meaning of Evolution, Yale Univer- 

 sity Press 



Courtesy of University of Michigan 

 Museum of Zoology 



