vi PREFACE. 
Vogt, Virchow, Moleschott, Müller, Rolle, Schleicher, 
Bleek, Meigs, Gliddon, Leidy, Cope, Gray, etc, to the 
medical and literary world generally, however, whose 
acquaintance with the writings of the distinguished savans 
just mentioned is necessarily superficial from the nature 
of their pursuits, we offer a brief but, we hope, a sufficiently 
detailed account of a subject which is not surpassed in 
interest by any other. We take this opportunity of thank- 
ing Prof. Hyrtl, Dr. Friedlowsky, Dr. Klein, of Vienna, 
Prof. Owen, Mr. Flower, of London, and Prof. Gervais, of 
' Paris, for their kindness in furnishing many facilities for 
study, as also of acknowledging our indebtedness to Profs. 
Leidy and Aitken Meigs for their many favors and sug- 
gestions, and to Dr. Nolan for materially assisting us in 
seeing this essay through the press. 
HENRY C. CHAPMAN. 
PARIS, June 21, 1872. 
