iv PREFACE. 



In this second part the author has ventured to differ in 

 some points from the majority of American students. Thus 

 he has been unable to recognise in the so called orders of 

 ornithologists groups of birds of more than family rank, while 

 their families are equivalent to genera in the other classes of 

 vertebrates. Again in the matter of nomenclature well-known 

 generic names have been retained, in spite of the law of priority. 

 These are the names of morphological literature, and to have 

 used Triturus, Molge, Myctophium, Zaglossiis ; to have mixed 

 up Esox and Belone would have served no useful end. 



A fair proportion of the illustrations are original ; as many 

 more have been engraved for the volume. These latter as well 

 as those borrowed have been credited as far as possible, to the 

 original source. The author would here return his sincere 

 thanks to Professor Robert Wiedersheim, Professor A. S. Pack- 

 ard, and Dr. Bashford Dean for cliches from their works. He 

 would also acknowledge his indebtedness to Professor C. S. 

 Minot, Dr. G. H. Parker, and Mr. F. A. Lucas for assistance in 

 connection with the manuscript. While many hundreds of 

 special articles have been read in the preparation of the work, 

 acknowledgement must be made to the aid received from W'ie- 

 dersheim's Anatomy, the Embryologies of Minot and Hertwig, 

 Zittel's Paleontologie, Jordan and Evermann's Fishes, Wood- 

 ward's Fossil Fishes, and Flower and Lyddeker's Mammals. 

 Woodward's Vertebrate Paleontology appeared in time to be of 

 assistance in the correction of the proofs. 



A work of this character must be largely a compilation. It 

 is impossible to settle all disputed questions by personal inves- 

 tigation, and one can only take those statements which seem 

 the most reasonable, and which appear to have the most sup- 

 port. That the volume will be found free from error is more 

 than can be hoped. The only apology the author can offer for 

 mistakes of judgment or of fact is based upon the large field, 

 the enormous literature, and the conflicting statements upon 

 many points. 



Tufts College, May 14, 1899. 



