THE GENEALOGY OF SHIPS. 305 



stances of graduation and consecutiveness were not com- 

 plete proof of the proposition; and to illustrate the fallacy 

 of that mode of reasoning I sent the following jeu $ esprit 

 to the journal which had been enterprising enough to 

 keep the popular reader posted in the progress of Pro- 

 fessor Marsh's discoveries: 



The intelligent public is placed under great obligations 

 to the Tribune for early and extended accounts of the 

 progress of American science. I have been extremely 

 interested in the bulletins of Professor Marsh's explora- 

 tions in the far West. The Tribune's re-presentation (in 

 the number for May 4) of the subject of extinct equine 

 quadrupeds on the American continent is entertaining 

 and instructive, and made intelligible by the reproduc- 

 tion of the striking cuts showing the progressive historical 

 changes in the foot of the equine animal. \ These, and 

 other similar facts, are often cited as evidence of the 

 genealogical descent of the domestic horse. The writer 

 of the article of May 4 seems to view them as evidences 

 that may sustain Mr. Darwin's theory, as he suggests 

 certain physical conditions which may have given few- 

 toed horses an advantage over many-toed horses. 



Now nobody can be insensible for a moment to the 

 beautiful exemplification of fundamental plan which we 

 discover in these forms; no one can deny that the series 

 constitutes an evolution; but some may question whether 

 Oroliippus, Mioliippus, Hipparion and Eqitus stand in genea- 

 logical relationship to each other. To clear up all doubt on 

 this question, and establish Darwinism on a scientific basis, 



* An excellent set of illustrations may be consulted by the reader in the 

 Popular Science Monthly, lv, 295, Jan. 1877. These have been reproduced in the 

 third edition of Dana's Manual of Geology, plate x. 



