APPENDIX. 



Art. XLIII. — Recent Polydactyle Horses • by O. C. Marsh. 



In this Journal for June, 1879, the writer made a brief 

 summary of the facts then known to him in regard to existing 

 horses with extra digits, especially in relation to the extinct 

 species he had discovered in the Rocky Mountains, and also 

 gave figures of typical examples of existing and fossil forms.* 

 Since then, he has collected much material bearing on the 

 question, particularly of extinct horses, and an illustrated 

 memoir on this subject has long been in preparation. Of 

 recent forms, a number of polydactyle specimens have likewise 

 been secured, some of which show new anatomical points of 

 interest, and are discussed in the present communication. 



In the article above cited, various recorded instances of 

 extra digits in the horse are mentioned, some dating back to 

 the beginning of the last century. A much earlier notice is 

 the account of the famous steed of Julius Cassar, given by 

 Suetonius (de vita Gcesaris, LXYI), to which a classical friend 

 has recently called the attention of the writer. According to 

 the historian, Csesar " used to ride a remarkable horse, which 

 had feet that were almost human, the hoofs being cleft like 

 toes. It was born in his own stables, and as the soothsayers 

 declared that it showed its owner would be lord of the world, 

 he reared it with great care, and was the first to mount it; 

 it would allow no other rider." 



It is now known to every one familiar with the modern 

 horse, that the main, functional toe of each foot is the third 

 digit, corresponding to the middle finger of the human hand 

 and foot. In addition to these, two " splint bones," one on 

 each side of the main cannon bone, are present beneath the 

 skin. It is not so well known, however, that the latter are the 

 remnants of two other toes possessed by ancestors of the horse. 



* Polydactyle Horses, recent and extinct, this Journal, III, vol. xvii, p. 497, June, 

 1879; see also by the writer, New Equine Mammals from the Tertiary, Ibid., vol. 

 vii, p. 247, March, 1874; Fossil Horses in America, Am. Naturalist, vol. viii, p. 

 288, May, 1874; and Introduction and Succession of Vertebrate Life in America, 

 this Journal, vol. xiv. p. 338, November, 1877. 



Am. Jour. Sci.— Third Series, Vol. XLIII, No. 256. — April, 1892. 

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