PREFACE. v 



of those in charge of the various collections. The principal changes 

 resulting in the manuscript were in the addition of a few species. 



That the book appears in its present form is also due to the Carnegie 

 Institution, on account of their acceptance of the manuscript for publication. 

 Were it not for this privilege, much of the illustrative material must have 

 been omitted. These many obligations I have felt keenly, and have 

 tried in a measure to meet by conscientious care in the execution of 

 every detail. 



UNIVERSITY OF PENNSYLVANIA, HENRY S. CoNARD, 



PHILADELPHIA, December i, 1904. Senior Harrison Fellow. 



