PREFACE. v 



the author has submitted the manuscript of certain chapters 

 to naturalists distinguished by their special knowledge of 

 certain groups. The manuscript of the sponges has been 

 read by Professor A. Hyatt ; of the worms and Mollusca, by 

 Dr. Charles S. Minot ; of the Eehinodenns, by Mr. Walter 

 Faxon; of the Crustacea, by Mr. J. S. Kingsley. Proofs of the 

 part relating to the fishes have been revised by Professor T. 

 Gill, whose classification as given in his "Arrangement of 

 the Families of Fishes," has been closely followed, his defin- 

 itions having been adopted often word for word. The man- 

 uscript of the Batrachians and Ileptiles has been read by 

 Professor E. D. Cope, whose classification, given in his 

 " Check-List of North American Batrachia and Reptilia," 

 has been adopted. Proofs of the part on birds have been 

 read by Dr. Elliott Coues, U.S.A., whose admirable "Key 

 to the Birds of North America" has been freelv used, the 



/ 



author's words having been often adopted without quotation- 

 marks. Dr. Co.ues has also revised the proofs of the pages re- 

 ferring to the Mammals. To the friendly aid of all these 

 gentlemen the author is deeply indebted. 



As to the illustrations, which have been liberally provided 

 by the publishers, a fair proportion are original. The full- 

 page engravings of the anatomy of the typical Vertebrates 

 have been drawn expressly for this work by Dr. C. S. Minot ; 

 a number have been prepared by Mr. J. S. Kingsley ; Prof. 

 W. K. Brooks has kindly contributed the drawing of the 

 nervous system and otocyst of the clam, and a few of the 

 sketches are by the author. 



The publishers are indebted to Prof. F. V. Hayden 

 for illustrations kindly loaned from the Reports of the U.S. 

 Geological Survey of the Territories ; a few have been 

 loaned by Prof. S. F. Baird, U.S. Commissioner of Fish and 

 Fisheries, and the members of the U. S. Entomological Com- 

 mission ; a number have been loaned by the Peabody Acad- 



