no NATURAL SCIENCE. Feb., 



To admit that one does not know what that bone is, is one thing ; 

 to ignore its existence is another. Whether it be right or wrong, I 

 shall for the present call it the ulnar e. Subsequent proof that it is 

 something else, e.g., a crocodilian " lenticulare," will not invalidate 

 my argument. 



The hand has been so much misrepresented both in words and 

 in drawings that I took it as an " awful example " in my contention 

 as to the sources of error. There are five digits and no fewer, and 

 I never suspected that it would be necessary for me to give further 

 proof than that already given in my essay on errors. Great as I 

 represented the power of a " dominant idea " to be, its power over the 

 minds of some persons, to whom I will refer in the sequel, appears to 

 be vastly greater even than I had guessed. To anyone who has 

 understood the evidence already brought forward and whose know- 

 ledge of mechanical principles is sufficient to enable him to assess its 

 value, what I have already adduced constitutes a demonstrative proof. 

 I will venture now to prove it over again by three distinct proofs, each 

 of which is in itself conclusive. 



(i.) Three long, slender fingers on each hand are plainly seen on 

 the Berlin slab. They are made up of two, three, and four phalanges 

 respectively, in addition to a metacarpal each. Each bears a claw, 

 which, though not easily made out in the photographs, especially in 

 the smaller photographs, is perfectly distinct in most cases in the 

 slab itself. There can be no doubt, and nobody does doubt, that 

 these three correspond to the digits I, II, and III respectively of the 

 normal pentadactyle reptilian fore-limb. The lengths of the various 

 metacarpals and phalanges in the Berlin specimen are as follows, 

 beginning at the proximal end, i.e., with the metacarpal, in each case : — 

 I. 8 + 20+1 1 =39 mm. 

 II. 27-5 + 154-19+13 = 74-5 mm. 



III. 264-5'5 + 4 + ? + ? = 44'5 mm. The joint between the third 

 and the ungual phalanx is hidden, but these two together measure 

 19 mm. Of these bones the second metacarpal is the largest, and at 

 its basal end it is under 4 mm. thick. 



Some of the bones corresponding to these are to be seen in the 

 London specimen ; but as they are displaced, it is not possible to 

 identify them with certainty. What Owen called the two terminal 

 phalanges of the digit I, closely resemble the two terminal phalanges 

 of digit II of the Berlin specimen, and I take them for these phalanges. 

 They measure respectively 22 mm. and 15 mm., i.e., they exceed the 

 bones of the Berlin specimen in the proportion of rather over 9 to 8. 

 To justify this determination I give the lengths of some other bones 

 in the specimens. The first number in each case is the length 

 of the bone in the Berlin specimen ; the second, that in the London 

 specimen. Ulna, 56mm., 63-5 mm.; Radius, 55 mm., 62 mm.; Femur, 

 51 mm., 58 mm. (?) ; Tibia, 71 mm., 81 mm. In each case except 

 that of the femur the ratio is almost exactly 8 : 9, and in the case of the 



