XX 



PREFACE 



and from living and preserved forms at hand. In some cases models, 

 charts, or texts now out of print were made use of. It was not possible 

 to trace the origins of a few of the figures. Regardless of source 

 every figure was redrawn or made diagrammatic and re-labelled 

 especially for this text. Figures adapted from original contributions 

 are acknowledged in the legends by the name of the investigator. 

 Cheerful acknowledgment is also made of permission to re-draw 

 with modifications from current texts published by the following: 

 The University of Chicago Press. The University of California Press. 

 Oxford University Press. P. Blakiston's Son and Co. W. B. Saunders 

 and Co. Henry Holt and Co. Longmans, Green and Co. McGraw- 

 Hill Book Co. The Macmillan Co. D. Appleton and Co. Harper 

 and Brothers. Gaston Doin et Cie, Paris. Georg Theime, Leipzig. 



J . William Buchanan 

 Evanston, May, 1933. 



