REVIEWS 3 2 9 



The two lower divisions, the Cuchara and Poison Canyon beds, were 

 found to lie unconformably below the Huerfano beds, and from the 

 presence of a species of Baculites it is supposed that they are Creta- 

 ceous deposits of marine origin. These Cretaceous beds were found 

 to be certainly not 800 feet below the summit of the upper Huerfano 

 beds, so that the observation affects not only the determination of the 

 age of the Poison Canyon and Cuchara beds, but materially reduces the 

 thickness of the upper beds. 



The only true Huerfano lake deposits are variegated marls, clays, 

 soft shales and sands, aggregating only 800 to 1000 feet in thickness, and 

 lying in a nearly horizontal position. In these beds, although with- 

 out doubt forming a continuous deposition, two distinct horizons were 

 identified from their inclosed vertebrate remains. The upper one of 

 these horizons, the one from which Professor Hills secured the major 

 part of his material, is of Bridger age. The lower horizon, however, 

 contains none of the forms characteristic of the Bridger level, but is 

 distinguished as of Wind River or of Wasatch age, by the presence of 

 several characteristic lower Eocene forms. 



Article XXII. A Revision of the Puerco Fauna. By W. D. Mat- 

 thew. Pp. 259-323. 



The Puerco fauna was first described by Cope in numerous papers 

 published between 1881 and 1888. Ninety-one species of mammals 

 were recognized, and to these three more were added by Osborn and 

 Earle in 1895. The original collections used by Cope are now the 

 property of the museum, and to these have been added important 

 collections made by the museum expeditions in charge of Dr. J. L. 

 Wortman. The present revision is based upon all of these collections, 

 and consists largely in a rearrangement of the species and a reduction 

 of their number, made possible by the more perfect material. 



The fauna of the upper Puerco beds is found to be entirely dis- 

 tinct from that of the lower beds, not a single species being common 

 to both, and in no case does a genus pass through without serious 

 modification of at least subgeneric value. Because of this difference 

 in the faunas, Dr. Wortman proposes to designate the upper beds by 

 the name Torrejon formation. 



The Puerco-Torrejon faunas are composed of the following ele- 

 ments : 



1. The Mesozoic group of Multituberculates culminates in the 



