382 



MERISTIC VARIATION. 



[part i. 



had does such a digit group itself into the Symmetry of the normal 

 manus ; but it stands apart, or is bent or adducted behind the other 

 digits, having a hoof which is irregularly pyramidal, curving in neither 

 direction especially. Such a digit has generally three phalanges, and 

 is of about the size of digit II, though not rarely it is large in size 

 approaching more nearly to III than to II (as Coll. Surg, Mus., Ter. 

 Ser., 297). 



Two extra digits internal to digit II, 



571. This condition is not less common than the last. The two extra 

 digits are borne either by two separate extra carpal bones (Fig. 119, c\ 

 c 2 ), or by one carpal imperfectly divided (Ercolani, I. c, PI. I., Jig. 6); 

 or the metacarpals of the extra digits simply articulate against the 

 carpo-metacarpal joint of II (as in a specimen in my own possession). 

 The extra digits may be double throughout, or the two may be com- 

 pounded in their proximal parts (Ercolani, I. c, PL i., fig. 5 ; also case 

 in Oxford Mus. 1 , 1506, a, in which the two extra digits were ill-formed 

 and of unequal size, having a common metacarpal). Fig. 119 shews 

 such a pair of extra digits in their most complete form. The central 

 part of the metacarpal of II has either never ossified or has been 

 absorbed. As bearing on the question of the relations of parts in 

 Meristic Repetition the fact of most importance is the circumstance 

 that the digits III and IV retain their normal Symmetry, but the two 



Fig. 119. Left manus of a Pig, No. 571. 



I. View from in front. II. View from inside to shew the convergence of 

 d 1 and c/ 2 towards each other. 



d 1 , d 2 , two extra digits placed internally, c 1 , c", two extra carpal bones with 

 which they articulate, sc, scaphoid, hi, lunar, cu, cuneiform, t, trapezoid. 

 m, magnum, u, unciform. <Z 3 — d 6 , the digits II, III, IV, V. 



1 For note of this specimen I am indebted to Mr W. H. Benham. 



