CHAP. XIII.] 



DOUBLE-FOOT : PECOKA. 



381 



[A case given by Eecolani (/. c. , p. 783, Tav. n., figs. 9 and 10) of similar 

 duplicity in a lamb seems to be very possibly a case of double monstrosity. In this 

 animal the hind limbs were altogether absent.] 



567. Calf, having five digits on one manus. There is nothing to shew positively 

 whether this specimen is a right or a left, and it is even possible that it is part of a 

 polymelian 1 . Carpal bones gone. Metacarpals four, disposed in two pairs. One 

 pair bear the digits d 4 and d 5 (Fig. 116), which 

 have a common proximal joint. Their ungual 

 phalanges curve towards each other, forming a 

 Minor Symmetry like those of a normal Calf. 

 The other two metacarpals bear three dibits ; two 

 (d 3 and d 2 ) articulate with one metacarpal having 

 a divided epiphysis. The other metacarpal bears 

 a digit (d 1 ) of full size curving towards d' 2 . The 

 ungual phalanges of d 2 and d 3 are nearly straight 

 [cp. Nos. 558 and 559.] C. S. M., Terat. Ser., 

 No. 299. 



568. Calf: left hind foot similar case : inner group 

 of tico toes curving towards each other and an 

 outer group of three toes of which the middle one 

 was almost bilaterally symmetrical while the hoofs 

 of the other two were each turned towards it. Five 

 metatarsals united but marked out clearly by 

 grooves. Tarsus much as in No. 566. Ekcolani, 

 I. c, p. 774, Tav. i. fig. 8. 



569. Calf: left hind foot a somewhat different case, 

 Dkew, Commercium Litterarium, Nuremberg, 1736, 

 p. 225, Taf. in. fig. 2. [Description meagre, but 

 figure good. Beginning from the inside the five 

 toes turned (1) outwards, (2) outwards, (3) inwards, 

 (1) outwards, (5) inwards, respectively. There were 

 only four metatarsals, (3) and (4) being both borne 

 on one metatarsal.] 



POLYDACTYLISM IN THE PlG. 



Fig. 118. Manus of a Calf, 

 No. 567. d\ d\ d 3 , group of 

 three digits [? internal] ; d 4 , d b , 

 group of two digits [? external]. 



570. 



Of the great numbers of feet of poly- 

 dactyle pigs recorded or preserved in 

 museums all I believe are fore feet. No 

 case of a polydactyle hind foot is known to 

 rae in the pig. All the cases are examples of proliferation upon the 

 internal side of the digital series. With very few exceptions the 

 variation takes one of two forms, consisting either in the presence of 

 a single digit internal to the digit II, or in the presence of two digits, 

 either separate or partially compounded, in this position. A very few 

 cases depart from these conditions 2 . The condition is very usually 

 the same or nearly the same in both fore feet. 



One extra digit, internal to digit II. 



Such a digit may either have a separate bone for its articulation in 

 one or both rows of the carpus (as Ercolani, /. c, PI. i. fig. 3), or it 

 may articulate with a half-separated extension of the trapezoid (as Coll. 

 Surg. Mus., Ter. Ser., 297 ^1), or with the metacarpal or other part of 

 digit II (very common), sometimes simply branching from this digit 

 without an articulation. In no case of which good accounts are to bo 



1 The Catalogue gives no indication on these points. 



2 For example a 1. fore foot in which the metacarpal of II. bears a rudimentary 

 digit on each side of the digit II, three in all. Eecolani, Mem. Ac. Bol., 1881, PL 

 I, fig. 1. 



