McMurrich, formerly of Haverford College; to Mr. H. A. 

 Pilsbry, of the Academy of Natural Sciences ; to Dr. George 

 Marx, of Washington; to Dr. P. R. Uhler, of Baltimore; to 

 the late Mr. G. H. BoUman, of Bloomington, Ind. ; and to two 

 of my immediate assistants, Messrs. J. E. Ives and Witmer 

 Stone. 



To Miss A. Peniston, of Peniston's, Bermuda, I am under 

 special obligation for the use of much new material illustrating 

 the Bermudian fauna ; and I am similarly indebted to Dr. W. H. 

 Dall, of the U. S. National Museum, Washington, for having 

 placed at my disposition the collection of Bermuda shells made 

 a few years ago by Mr. G. Brown Goode. 



Finally, I desire to convey my thanks to the members of 

 my class — Messrs. J. E. Ives, Witmer Stone, Eoberts Le Bou- 

 tillier; Misses Emma Walter, Mary A. Schively, Virginia 

 Maitland, Emily G. Hunt, Ella Hunt — all of whom rendered 

 much valuable assistance either in the field or in the labora- 

 tory. 



A. H. 



Academy of Naturai, Sciences, 



Philadelphia, September, i88g. 



