of the Hand in Pip-i antl Xcnopus. 



205 



vvliicli cannot be seen from tlie dorsal side ot' tlic liand, on 

 account of the outer metacarpals lying at a higher level than 

 the middle ones, and thus being able to move inwards over 

 the middle fingers, as in Pipa : moreover these authors must 

 have regarded the sesamoid bone (represented in dotted lines 

 /. c. lig. 4) as ventral in Xenopus as well as in Pijxi, other- 

 wise they would have pointed out its different position ; 

 in the skeleton whicii I have examined it touches the radius 

 only, while Howes and iiidewood have found it lying in the 

 line of junction between the ulna and radius. 



Owing to this error in confusing the ventral and dorsal 

 sides of the hand in Xenopus, and as the figure of Howes 

 and Ividewood does not depict the surface of the carpal 

 bones, though it is of some value for comparison with /Y/;«, 

 I have thought it best to give fresh figures without entering 

 into further details as to the siniile bones. 



Fiff. 



Fiff. 6. 



Left hand of Xenopus l<evis (Daud.). Fig. 5 seen from the dorsal side, 

 fig. 6 from the volar side. R, radius ; U, ulna ; r, radiale ; u, uluare ; 

 C, centrale ; Cj-Cj, carpalia 1-5; II-V, metacarpalia II-V; s, sesa- 

 moid bone. 



The metacarpals and the fingers are veiy slender; the 

 metacarpals, of which the middle ones are the longest, are 

 neither so long nor aberrantly curved as in Pipa : of the 

 fingers the penultimate (IV) is the longest, next comes the 

 outer (V), then the third (III), and the innermost (II) is 

 shortest ; but the difference in length is rather small, so that 

 at a first glance they seem almost equal. In most Anurans 

 the distribution of the colour on the fore limbs is very charac- 

 teristic, the side looking towards the body being pale, as is 

 the back of the hand, except the two outer fingers (IV, V), 

 which are coloured ; the same condition is partly seen in 

 XenopuSj especially in A''. Icevis^ where I have found the back 



