88 REVIEWS 



remembered that some of the "best authorities" are among those who 

 assert "that these reptiles do not form a natural group, but belong to 

 divisions remotely connected and not derived from a common stock." 

 It is, to say the least, a very open question whether the groups defined 

 as the orders Theropoda, Saiiropoda, and Predentata are not distinct and 

 unrelated. 



The Dinosaurs are discussed in the order of their appearance in 

 time. The Triassic Dinosaurs come under Part I and are followed by 

 the Jurassic and Cretaceous forms in Parts II and III. These parts 

 are confined to descriptions of the anatomical characters of the various 

 forms and their distributions. The author discusses briefly in this 

 connection the European forms and their relations to the North 

 American forms. 



Part IV is taken up with a general discussion of the relationship of 

 the Dinosauria to the Aetosauria, Crocodilia, Belodontia, and Aves, to 

 all of which groups he finds many points of similarity. 



Part V is devoted entirely to a classification of the group which he 

 regards as a distinct subclass Dinosauria, with three orders Theropoda, 

 Sauropoda, and Predentata. The order Theropoda contains ten fami- 

 lies and the four suborders Cceluria, Compsognatha, Ceratosauria, and 

 Hallopoda. The order Sauropoda contains six families and no subor- 

 ders. The order Predentata contains eleven families and the suborders 

 Stegosauria, Ceratopsia, and Ornithopoda. 



Professor Marsh has retained the opinions which he has expressed 

 in his former publications on the same subject, many of which have 

 been criticised and controverted in current scientific literature, so that, 

 while the work will find its chief, and a great value, to the reader who 

 has not access to scientific periodicals, he must not lose sight of the 

 fact that the taxonomic position of the animals comprising the hetero- 

 geneous group called Dinosaurs is still an unsettled question. 



E. C. C. 



