chap, xiii.] DIGITS OF HORSE '. SPECIAL CASES. 



371 



C. Intermediate cases. 



53, 



m 



td 



H \\ HI ! I IV 



•t» 



We have now seen cases of increase in number of digits oc- 

 curring by addition to the series, and cases occurring by division 

 of III. It may at first sight seem impossible that there can be 

 any process intermediate between these two. Nevertheless the 

 word sufficiently nearly describes the condition of at least the first 

 of the following cases, and is to some extent applicable to the 

 second also. If the condition shewn in Fig. 112 be compared with 

 those in Figs. 106 and 110 it will be seen that it is really inter- 

 mediate between them. 



Horse (young): right manus with internal supernumerary digit. 

 The bones are not in place, but have been attached with wires. 

 The condition is as follows. The distal series of carpus remains and 

 is normal or nearly so. Of the splint-bones, the inner (mcp. II) is 

 thicker than the outer mcp. IV, but it is very 

 little longer. The large metacarpal (III) is 

 almost, but not quite, bilaterally symmetrical 

 about its middle line. In the distal epiphysis 

 the asymmetry is distinct, the internal side of 

 the epiphysis being less developed than the 

 external side. This epiphysis bears a large 

 digit of three phalanges, but instead of being 

 bilaterally symmetrical, like the normal toe of 

 the Horse, each of the joints is flattened on the 

 internal side, the flattening increasing from the 

 first to the third phalanx. The hoof is greatly 

 flattened on its inner face. 



Internally to the epiphysis of the digit III 

 there is a separate small bone, representing the 

 distal end of an inner metacarpal. This bone 

 bears a digit with two phalanges, and a hoof 

 which is flat on the side turned towards the 

 other hoof, like that of a calf, though it only 

 reaches to the top of the larger hoof. The 

 first phalanx of this digit is imperfectly divided 

 by a suture into two parts. This division is not 

 that of the epiphysis from the shaft. This extra 

 digit may be thought to be that of mcp. II, 

 but it is clear that it was in part applied to 

 mcp. III. Note also that mcp. Ill is modified 

 in correlation with its presence. Coll. Surg. 

 Mas., in Terat. Cat, No. 301. 



The foregoing case well illustrates the inade- 

 quacy of the view on which an individuality is 

 attributed to members of the digital series. 

 The smaller digit in it is as regards the Sym- 



Fig. 112. Eight 

 manus of a horse, 

 No. 553, from behind, 

 m, magnum, td, tra- 

 pezoid, it, unciform. 



(From a specimen 

 in Coll. Surg. Mus.). 



24—2 



