POPULAR BOOKS ON EXTINCT ANIMALS.
If 'Dragons of the Air,' by H. G. Seeley, is not in quite so popular a vein as its title might indicate it is none the less a clear, comprehensive and interesting account of that remarkable group of reptiles, begging Professor Seeley's pardon, known to science as pterodactyls. No one is better qualified than Professor Seeley to write of them, as his acquaintance with these flying dragons is of many years standing, and he has made them the objects of special study. He tells us that he has attempted to show how a naturalist does his work and illustrates the methods of the paleontologist by briefly comparing the various parts of existing flying creatures with one another and applying the information thus gained to the study of the skeleton of the pterodactyls. Part by part the various portions of this skeleton are passed in review, and we are told the more important variations found in the widely varying members of the group and between them and other flying animals. Then, after a chapter devoted to evidences of animals' habits, from which the reader may learn how the conclusions regarding the food, covering and flight of pterodactyls have been reached, we are introduced to the various species that have existed at different periods of the earth's history. In connection with this are given some restorations of the more remarkable of the dragons of the air, including the extraordinary Dimorphodon with a head bigger than its body. Accompanying these restorations are plates showing the specimens on which they are based, and the skeletons built up from these specimens. Most of the figures represent the animals as running on all fours, an attitude that is questioned by some of our paleontologists, notably by Dr. Williston, who considers that they walked on the hind legs alone and that the great Ornithostoma in particular could not possibly have used its fore limbs as legs. The concluding chapters contain a discussion of the relations and origin of the pterodactyls and, from what has been said in other parts of the book, we are in a measure prepared to find that Professor Seeley advocates a closer affinity between birds and pterodactyls than is usually accorded them. Most anatomists will probably in considering that many features of the skeleton of pterodactyls, such for example as its remarkable pneumaticity are due to modifications for flight, but the author considers that Pterodactyls and Birds form two parallel groups which may be regarded as ancient divergent forks of the same branch of animal life. But whether we accept all Professor Seeley's deductions or not we may safely accept his facts and we are indebted to him for having placed so much information within our reach and for having given it in so readable a form.
'Animals of the Past,' by Frederic A. Lucas, is more popular in its line than 'Dragons of the Air,' and wider in its scope, dealing with a number of the more striking or more interesting of extinct animals and especially with those of gigantic size. Here, however, Mr. Lucas's mission in life appears to be to correct the widespread impression that the animals of the past were so very much larger than those of the present. Some of the dinosaurs we are told were the largest animals that