366 MEMSTIC VARIATION. [part i. 



lettered on the other and in the case of polydactyle horses, more 

 usual method. 

 '536. Horse: right manus with extra digit (Fig. 108). The distal 

 row of the carpus is present. It consists of four bones, the unci- 

 form, magnum and two other bones. Of these that lettered T 

 on the view of the Catalogue must be supposed to be the normal 

 trapezoid, while ac is considered to be an intercalated bone, perhaps 

 an additional os magnum. The unciform bears a splint-bone, 

 namely mcp. IV. The magnum bears a fully-formed mcp. and 

 digit III. With the bone ac articulates a large and substantial 

 metacarpal with a digit of three phalanges and a hoof, while the 

 bone T bears another splint-bone, marked II in the figure on the 

 hypothesis that the digit ac is not to be reckoned. Cat. Mus. Coll. 

 Surg., Terat. Series, 1872, No. 304. As mentioned above, it would 

 be more consistent with fact to count the bone ac as trapezoid with 

 mcp. II and the bone T as trapezium with mcp. I. 



.537. Horse having both fore feet (Fig. 107, A) as in the last case, the 

 hind feet bein^ in the condition described in the last Section, No. 535. 

 Marsh, Am. Jour. Sci., xliii. 1892, p. 3-40, Jigs. 3, 6, and 8. 



538. Foal having right manus closely resembling the above, the other 

 limbs being unknown. The mcp. I was longer than the normal mcp. 

 II. In this case the metacarpal II was partially united to mcp. Ill at 

 the central end but was free from it peripherally. vVehenkel, J. M., 

 La Polydactylie chez les Solipedes, from the Journal de la soc. r. des 

 sci. med. et nat. de Bruxelles, 1872, Jig. 2. 



Probably the feet of a large number of polydactyle horses would be 

 found to be in this condition if examined. Marsh, I.e., mentions three 

 other cases known to him in Yale Museum. 



c. Five metacarpals. 



539. Horse having Jive metacarpals and one supernumerary digit in 

 the left manus, and four metacarpals with a similar supernumerary 

 digit in the right manus. 



In the left manus with the trapezoid there articulated a well- 

 developed metacarpal II bearing the extra digit. Internal to this 

 was a trapezium bearing a splint-bone, 6 cm. long, 1'5 wide at 

 proximal end, representing metacarpal I [as in Section (1) b] 

 coalescing peripherally with III. On the external side of III the 

 splint-bone IV was present as usual. The case is remarkable from 

 the fact that external to the metacarpal IV there was another 

 rudimentary metacarpal, presumably representing V. This bone 

 was distinctly separated from IV at the central end, but was for 

 the most part united with it. Putz, Deut. Ztschr. f. Thierm., 1889, 

 XV. p. 224, figs. [The figures illustrating this paper are 

 carefully drawn. The representation of mcp. I is quite clear, but 

 the condition of the mcp. V cannot be well seen, as the whole foot 

 is represented with its ligaments, &c, which partly conceal the 

 structure. The whole account is very minute and gives confidence 

 in the statements.] 



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