20 PREFACE 



facilities at the U. S. National Museum, and for much critical advice in 

 connection with the account of the Mollusca ; to Dr. Henry A. Pilsbry for 

 assistance and for the use of the rich collections of the Philadelphia 

 Academy of Natural Sciences; to Dr. H. B. Kiimrnel, the State Geologist, 

 and Dr. M. W. Twitchell, the Assistant State Geologist of New Jersey, 

 for the use of the collections of the Geological Survey of New Jersey; 

 and to Mr. George S. Barkentin, of Albany, New York, for the beautiful 

 drawings which illustrate the Vertebrata, Mollusca, Brachiopoda, and 

 Echinodermata. Acknowledgment is also made to Mr. A. B. Bibbins for 

 several of the photographs of characteristic Upper Cretaceous outcrops. 



