100 REVIEWS 



The University Geological Survey of Kansas. Vol. IV. Paleon- 

 tology. Part I. Upper Cretaceous. Samuel W. Willis- 

 ton, Paleontologist. Topeka, 1898. 



It is with much interest that we examine this work on the paleon- 

 tology of Kansas. Professor Williston and his associates have made a 

 successful effort to produce a work of popular as well as scientific value. 

 The effort is worthy of commendation. The manner in which the sub- 

 jects are presented cannot fail to make the book useful in many places 

 where a purely scientific work would be of little value. 



Professor Williston reviews the work on Birds, Dinosaurs, and Croco- 

 diles ; but the most interesting and instructive part of his work is the 

 monograph on the Mosasaurs. While his work is primarily with the 

 Kansas Mosasaurs, he does not confine his study to these, but briefly 

 and concisely covers the whole subject. Here, especially, he has been 

 successful in keeping the interest alive. 



The monograph opens with a brief historical summary of the Mosa- 

 saurs — their discovery and the publications concerning them. This is 

 followed by their range, distribution, and classification. He refers to the 

 controversies over the relations of these reptiles, and arrives at the conclu- 

 sion from his own study, that they are entitled to be classed as "an inde- 

 pendent group among the Lacertilia." In this connection he quotes 

 the classification proposed by Dr. Baur. The greater part of the mono- 

 graph is devoted to a careful anatomical comparison and description 

 of these interesting reptiles, many of which the author originally dis- 

 covered and described. No pains have been spared to make the work 

 complete and useful. 



In his systematic descriptions Professor Williston points out a num- 

 ber of facts of popular, as well as scientific interest. The Mosasaurs 

 are described as "varying in length between five and forty feet," a 

 decided reduction in size from the Mosasaurs of the text-books, which 

 are given a maximum length of 100 feet. Another fact which seems to 

 have escaped the notice of former collectors is the deformation of the 

 bones undergone in the process of fossilization, especially in the Nio- 

 brara formation. The bones have yielded as if made of plastic mate- 

 rial. The deformation has furnished the characters upon which many 

 new species have been based. The author concludes that this will cut 

 out about four fifths of the species that have hitherto been described. 



The turtles are described by Professor Williston and Professor E. C. 

 Case, and the microscopic organisms by C. E. McClung. 



