PREFACE. V 



The measurements are given in decimal fractions of an inch (as 

 in the former volumes of these monographs). 



I am under manifold obligations to my friends Director Loew, 

 of Guben, Prussia, and Dr. Schiner, of Vienna, for their assistance 

 in my work. 



R. OSTEN SACKEK 



New York, April, 1868. 



