22 



SCIENCE. 



[N. S. Vol. XX. No. 496. 



criticism, ' This book is filled with just such 

 mistakes throughout, notably a figure of a 

 sabre-toothed tiger in fierce combat with a 

 hairy mammoth.' Near the town of Hen- 

 nessey, Oklahoma, Professor Cope obtained 

 teeth and boiies of the mammoth associated 

 with the bones of a sabre-toothed cat as large 

 as a lion, as though ' death had overtaken it 

 while feeding upon the carcass of the mam- 

 moth ' (J. Acad, of Nat. Sci., Phil., IX., page 

 453.) It is doubtless unnecessary to state that 

 the illustration will stand as an accurate por- 

 trayal of a combat which man of the mid- 

 Pleistocene period undoubtedly witnessed many 

 a time. 



Since Dr. Gill's criticisms appear to be based 

 upon the statements made in Dr. Case's letter 

 and not upon an examination of the book at 

 first hand, they need little attention. There 

 are a few statements, however, which the 

 reader may be interested in comparing with 

 statements of other eminent scientists. 



Dr. Gill states, ' But no ungulate in the line 

 of the horse with five toes has been discovered.' 

 Professor Cope writes (' Origin of the Fittest,' 

 page 301) : " Phenacodus is antecedent to all 

 the horse series, the elephant series, the hog, 

 the rhinoceros and all other series of hoofed 

 animals. It has five toes on all of the feet." 



Again Dr. Gill writes : ' Another pure as- 

 sumption is that the primitive equoidean ani- 

 mals lived especially in the marshes.' Pro- 

 fessor Huxley in his American Addresses, re- 

 fers to the Eocene horses as ' the short-legged, 

 splay-footed plodders of the Eocene marshes.' 

 Professor Cope writes (' Origin of the Fittest,' 

 page 374) : " * * * the types with reduced 

 digits are dwellers on dry land in both orders, 

 and those that have more digits are inhabitants 

 of swamps and mud. * * * Certain it is 

 that the lengths of the bones of the feet of 

 the ungulate orders have a direct relation to 

 the dryness of the ground they inhabit, and 

 the possibility of speed which their habitat 

 permits them, or necessarily imposes on them." 

 (See, also, Mr. Lucas's statement, McOlure's 

 Maijazine, volume 15, page 517.) 



Still again Dr. Gill writes, ' But there is no 

 need of confining such animals to the marshes.' 

 Had Dr. Gill read the next few pages of the 



text he would have been spared the trouble of 

 making the remark. 



Dr. Gill is certainly correct -in stating, 

 ' Every instructed zoologist would know that 

 such a characteristic as five toes (or four) 

 must necessarily be coordinate with innumer- 

 able modifications of other parts,' but ,one 

 can scarcely be expected to present all of 

 ' these innumerable modifications ' to the child 

 of seven years. In presenting a brief account 

 of the changes that took place in the feet and 

 in reserving the changes in the structure of 

 the teeth for a later period, I find support in 

 the statement of Professor Cope (' Origin of 

 the Fittest,' page 269), where he states, " The 

 primary forms of mammalia repose in great 

 measure on the structure of the feet. Those 

 of the teeth are also significant, but present a 

 greater number of variations among animals 

 otherwise nearly related." 



While not a specialist in paleontology or in 

 several of the sciences to which I find it neces- 

 sary to go for materials, I have taken great 

 pains to secure reliable data, and to consult 

 with specialists concerning the same. Since 

 Dr. Case's criticism was made. Dr. S. W. 

 Williston, professor of paleontology of the 

 University of Chicago, has kindly examined 

 ' The Tree-dwellers ' from the point of view 

 of the paleontologist; and he has given me 

 permission to state this fact in this letter and 

 in the preface to the second edition of the 

 book. In view of the 'fact that Dr. Case states 

 that the book is filled with glaring errors, the 

 reader may be interested in knowing that Pro- 

 fessor Williston has authorized me to( state 

 that aside from the changes made in the lesson 

 on the wild horse referred to above, the 

 changes he suggests are few and unimportant. 



It is too much to expect a series of books 

 which represents such a radical departure 

 from traditional text-books for children as this 

 series does, to pass unchallenged. But this 

 is not a matter to be regretted. That which 

 causes one to review one's work, to weigh evi- 

 dence more carefully, to eliminate errors, to 

 reconstruct in the light of a higher truth, 

 should be welcomed by all. A careful ex-- 

 amination and criticism of the series is in- 

 vited, with the assurance that the points which 



