REVIEWS. 751 



The Colorado Formation and its Invertebrate Fauna. By T. W. 

 Stanton. Bull. U. S. Geol. Surv., No. 106, 288 pp., 45 

 plates. Washington, 1893. 



In the preparation of this memoir the author has made extensive 

 field studies in Colorado and Utah, and has had the benefit of certain 

 unpublished notes by Mr. Walcott on the Kanab valley. In addition 

 a careful review of previous papers and collections has been made with 

 the satisfactory result that, whereas previously but twenty-five or thirty 

 species had been definitely referred to the Colorado formation, one 

 hundred and fifty are now listed. The greater portion of these, includ- 

 ing some thirty-nine new forms, are described in this paper. 



The history and definition of the Colorado formation is introduced 

 by Meek and Hayden's Upper Missouri section, which has so long 

 been the starting point for all work on the interior Cretaceous. The 

 evolution of this section from the original five numbered formations 

 to the present form is briefly sketched. 



The Cretaceous is considered by regions, beginning with Iowa, and 

 continuing through Kansas, Upper Missouri region, Colorado, New 

 Mexico, and Utah. The portion devoted to Colorado and Utah is 

 particularly full and interesting. 



The Colorado fauna is compared with those of other marine Cre- 

 taceous formations. There are fourteen identical or very closely 

 related forms which occur in both the Colorado and Montana. The 

 Eagle Ford shales contain twelve typical Colorado forms, and the 

 Austin limestone thirteen. Seven species are found in British America, 

 and eight in Manitoba. A comparison with European formations 

 shows the relations to be closest with the Turonian. 



The species described are well figured, and the descriptions clear 

 and concise. A large number of changes in nomenclature are made, 

 many of which result from the changes in classification adopted by 

 recent European writers. Few of the changes made will be more 

 widely noticed than that of Inoceramus problematicus Schlot, the best 

 known and most widely distributed Colorado form, to Inoceramus 

 labiatus, a form described earlier (18 13) by the same author. Another 

 of the changes which deserves notice is the recognition of the western 

 forms hitherto known as Gryphcea pitcheri Morton as belonging to an 

 independent species which is christened newberryi. Still another 

 change of importance is the recognition of Meek's American species 



