Wilder.] 4 [May 16, 



On the inner or tibial border of each hind foot is an extra digit 

 •which comes off about one inch and a half above the tip of the foot ; 

 it is small and closely resembles the thumb on the fore foot of ordin- 

 ary cats. But in this individual, the thumbs, instead of being short 

 and of little practical importance, are larger and longer than any 

 other digit ; on the left foot is a small supernumerary i:igit coming off 

 like a bud from the ulnar border of the thumb, while on the right 

 foot is a similar one, and in addition a second coming off from the 

 radial border of the thumb. 



The effect of these extra toes is to make the fore paw very large, 

 like a hand with a thick mitten or glove ; and this cat is certainly 

 somewhat noted for her climbing powers, as well as for using her 

 hands in other respects more effectively and dextrously than usual. 

 Her three kittens possess the extra toe upon the hinder foot, but the 

 thumbs, though larger than usual, are single. 



It would be interesting to ascertain, by comparison of specimens, 

 and published accounts of supernumerary digits, whether they occur 

 more commonly on the anterior or posterior extremities, whether upon 

 the right or left sides, and whether upon the inner or outer borders 

 of the feet ; this I have not yet had time to do, but the simple fre- 

 quency of this kind of monstrosity is, in my opinion, an indication 

 that only to a very slight extent, if at all, is the number of the digits 

 themselves or that of their phalanges to be taken as a basis for mor- 

 phological comparisons. The hands and the feet are the terminal 

 segments of parts which are themselves comparatively teleological 

 appendages of the antei-ior and posterior poles of the main axis of the 

 vertebrate body, and are therefore as far as possible removed from the 

 morphological centre of the body, which may reasonably be located 

 at or near the middle of the vertebral column, where the ossification 

 of the bodies, or centi*a of the vertebras commences, and from which 

 it advances forward and backward. 



The question will arise whether such duplications are not similar in 

 nature to those which result in more or less complete double monsters, 

 and which are referred to a more or less complete coalescence of two 

 more or less perfect individuals : in which case their occurrence 

 would have no signification outside of the domain of Teratology. 

 But if, as seems to me the case, such supernumerary parts at the dis- 

 tal extremities of the limbs are rather instances of simple vegetative 

 repetition of elements whereof several normally exist in a series, as 

 with the caudal vertebrae of the tailed mammalia, — then it is evidently 

 unsafe to depend upon them for the determination of morphological 

 problems. 



It would be as reasonable to define the sacrum, from its position in 

 man, as that compound bone behind which are only four coccygeal 



