1898.] 



AITATOMT OP PEDETES CAFFEE. 



863 



and described by Bardeleben ^ : it consists oi: two joints, of which 

 the proximal is a rod 14 mm. in length, thickened at either end 

 and stretching inwards across the palm ; the distal joint is 7 mm. 

 long, flattened from the palmar to the dorsal surface, and broader 

 than the proximal ; its long axis is directed outward, so that with 

 the proximal joint it forms an acute angle (see fig. 2, p. 867). The 

 metacarpal bone of the poller is very short ; it is parallel and in 

 the same plane as the other four metacarpals and is not at all 

 opposable (see fig.l). 



Fig. 1. 



Dorsal view of cai-pus of Pedetes caffcr, with radial ossicle flattened out 



In the foetal specimen no centres of ossification were present in 

 the carpus ; in the metacarpus centres were present for the shafts 

 of the index, medius, and annularis, but not for the pollex or 

 minimus. The praepollex or radial ossicle, as perhaps it will be 

 wiser to term it while its real nature is sub jucUce, is a cartila- 

 ginous bar corresponding in shape with the adult structure, but 

 no joint between the two segments could be made out ; there were 

 no ossific centres. It will thus be seen that the evidence which 

 this foetal specimen has to give on the radial ossicle is chiefly 

 negative : the structure is apparently a cartilaginous constituent 

 of the carpus from an early period, but how and when it ossifies 

 remains to be seen. It is interesting to notice that the three 

 metacarpals which are most permanent in the mammalian class 

 are the ones which, in this animal, ossify first. If this rule 

 holds good, it could not be expected that the radial ossicle, if it be 

 a prsepoUex, would ossify until after the minimus and pollex have 

 done so. In D'qnis there is a single bony bar stretching across 

 the palm and articulating with the radial side of the scapho-lunar ; 

 it has the palmaris longus inserted into its free extremity 



' P. Z. S. 1889, p. iitJO. 



