92 THE ZOOLOGIST. 



pteron founded on a caterpillar? The answer would almost 

 certainly be in the affirmative now, but posterity might reverse 

 the verdict ! 



Sixteenth Annual Report of the United States Geological Survey. 

 1894-95. By C.D.Walcott, Director. Washington. 1896. 



This bulky volume is another instance of how science is 

 fostered in the United States, and is the first report made by 

 Mr. Walcott, who succeeded Mr. Powell in 1894, after that 

 gentleman had directed the survey for thirteen years. We wish 

 the present editor equal success and increased longevity. 



With the geological contents of the volume we have nothing 

 to do in the pages of this magazine, but zoologists may well 

 consult and study an exhaustive memoir, by Prof. 0. C. Marsh, 

 on " The Dinosaurs of North America." As the author writes, 

 among the many extinct animals that lived in North America in 

 past ages, " none were more remarkable than the dinosaurian 

 reptiles which were so abundant during Mesozoic times. This 

 group was then represented by many and various forms, 

 including among them the largest land animals known, and 

 some, also, very diminutive. In shape and structure, moreover, 

 they showed great variety, and in many other respects they were 

 among the most wonderful creatures yet discovered." 



It is stated that the best authorities now regard the dino- 

 saurs as constituting a distinct subclass of the Reptilia, and 

 Prof. Marsh recognizes three groups, viz. Theropoda, carnivorous 

 forms ; and Sauropoda and Predentata, both herbivorous groups. 

 " The first of these suborders contains large dinosaurs more or 

 less protected by a dermal covering of bony plates ; the second 

 group includes the huge horned dinosaurs ; and the third is 

 made up of the forms that in shape and structure most nearly 

 resemble birds." 



While the geological range of the Dinosauria, according to 

 present knowledge, is confined entirely to the Mesozoic period, 

 known so well as the Age of Reptiles, their geographical distri- 

 bution was extensive. America, Europe, Asia, Africa, and Aus- 

 tralia, have all contributed remains of these animals, but " while 

 North America seems to have contained the greatest number of 

 different types, some of the larger species are now known to have 



