TAXEOPODA. 



375 



The internal relations of this vast division are readily determined by 

 reference to the characters of the teeth and feet, as well as other less im- 

 portant points. I have always insisted that the place of first importance 

 should be given to the feet, and the discovery of various extinct types has 

 justified this view. The predominant significance of this part of the skel- 

 eton was first appreciated by Owen, who defined the oi'ders Perissodactyla 

 and Artioductyla. Professor GilP has also used these characters to a certain 

 extent, but without giving them the exclusive weight that appears to me to 

 belong to them. Other authors have either passed them by unnoticed, or 

 have correlated them or subordinated them to other characters, in a way 

 which has left the question of true aftinity, and therefore of phylogeny, in 

 a very unsatisfactory condition. Much light having been thrown on these 

 points by recent discoveries in paleontology, the results as they appear to 

 me are here given. 



Carpus. — It is well known that in the Peris- 

 soflacfi/Ja and AriiodactyJa the bones of the two r%^"' „^^5s^'iyi 



rows of the carpus alternate with each other; 

 that the lunar, for instance "Iolo on the unci- 

 form, and to a varying degree on the magnum, 

 and that the scaphoides rests on tlie magnum ( 

 and to some degree on the trapezoides and 

 trapezium. It is also known that in the Pro- 

 boscidea another state of affairs exis^^; i. e., that 

 the bones of the two rows do ".ot alternate, but ^'<^- n-Left anterior foot of Eie- 



pliaa africaniis (from De Blainville). 



that the scaphoides, lu'^-ar, and cuneiform, rest One-tenth natural size. 

 directly on the trapezium and trapezoides, the magnum, and the unciform 

 respectively. The preceding characters are sometimes included in the 

 definitions of the respective orders. Further than this they have not been 

 used in a s^ocematic sense. 



^xofessor Gill says of the carpus of the Hi/racoidea, "carpal bones in 

 vwo interlocking rows ; cuneiform extending inwards (and articulating with 



'Arrangement of tlie families of Mammals prepared for the Smithsonian Institntiou. Miscel- 

 laneous Collections, 230. Nov., 1872. 



