.IiXE U, 1895.] 



SCIENCE. 



6G1 



codon, etc.. wc find tliat the degree of advanee 

 displayed by these forms is not so very great 

 and that it does not involve any very long 

 lapse of time. The radical difierence be- 

 tween the two faunas consists in the ordinal 

 groups which are present in one and not in 

 the other. Thus the Puerco has neither 

 artiodactyls. perissodactyls nor rodents, 

 while the AVasatch has no I^Iultituberculata 

 and relatively few Condylarthra. and the 

 creodonts of the two formations belong, for 

 the most part, to quite different types. The 

 obvious significance of these facts is that at 

 some time between the Puerco and the 

 Wasatch a great migration of mammals 

 ft-om some other region took place and 

 revolutionized the character of the Xortli 

 American fauna. 



A distinction that is likely to be fruitful 

 of important results is Osborn's diAision of 

 the placental mammals into the Mesopla- 

 centalia, of early and more or less Mesozoic 

 type, and the Cenoplacentalia. characteristic 

 of later Tertiary and recent time. " The 

 ditl'erence between these two groups consists 

 mainly in the lower state of evolution and 

 apparent incapacity for higher development 

 exhiliited bj- the Mesoplacentals. in contrast 

 with the capacity for rapid development 

 shown bj- the Cenoiilacentals." It can 

 hardly be right, however, to include the 

 creodonts in the lower group, since they 

 not only underwent a great expansion in 

 the Puerco, but in later times they also 

 gave rise, by independent development 

 along at least three lines, to the true Car- 

 nivora. Such a group cannot be fairly 

 charged Avith ' incapacity for higher de- 

 velopment.' 



This necessarily brief review cannot do 

 more than indicate the many points of un- 

 usual interest in this paper, and must refer 

 to the original those who would learn more 

 of it. 



W. B. Scott. 



Prixceton" College. 



The Oniitholurjij of IllinoU; Descrijjtive Cata- 

 logue. By RoBEkT RiDGWAY. Published 

 by authority of the State Legislature. 

 Vol. II. May, 1S95. Large 8°, pp. 282, 

 pis. 3.3. 



Ridgways Ornithology of Illinois has a 

 curious history. It was conceived by the 

 able Director of the Illinois State Labora- 

 tory of Xatural History. Prof. S. A. Forbes, 

 who twelve years ago asked the leading 

 American ornithologist to undertake its 

 preparation. Mr. Ridgway finished the 

 manuscript early in July, 1885. The firet 

 volume was finally ijrinted, but the entire 

 edition, together with the plates and cuts, 

 was destroyed bj' fire. This was in Febru- 

 arj', 1887. It was reprinted from proof 

 sheets, and proof of the reprint was not 

 submitted to the author. It was issued in 

 November, 1889. 



By a singular fatality, the manuscript of 

 the second volume was consumed in the 

 same fire : and, excepting proof of the first 

 90 pages, which was preserved, the entire 

 book had to be rewritten. This formidable 

 and di.sheartening task was accomplished 

 in 1891, and the printed book has just been 

 received (May 7, 1895). 



The original plan contemplated two dis- 

 tinct parts : Part I.. Descriptive Catalogue, 

 by Robert Ridgway : Part II., Economic 

 Ornithology, by S. A. Forbes. The present 

 volume comijletcs the Descriptive Catalogue, 

 and it is earnestlj' hoped that the volume 

 on Economic Ornithology will follow ; 

 though the labor of prei>aring such a work 

 is too great to be accomplished in a single 

 lifetime or bj- a .single man. 



The first volume is prefaced by an intro- 

 duction of S.J pages, treating of the physical 

 features of the State, the climate, and charac- 

 teristic features of the avifauna, and end- 

 ing with a bil>liograpliy. The systematic 

 part begins with a key to the higher groups, 

 which are arranged in the old style, the 

 Thrushes coming first. The orders, fami- 



