86 PROFESSOR STRUTHERS. 



epiphysis of the distal bone, and the parts on either side of the 

 distal joint as potentially a phalanx and its two epiphyses. 

 Possessing the cartilaginous elements above indicated, ossifica- 

 tion might thus give additional phalanges as follows, to digit 

 II., 2 ; to digits III. and V., 1 ; to digit IV., 2. 



10. The Bones of the Digits — Relative Length of the Digits. 

 — Eeferring to Table III., it is seen that digit III. is the longest, 

 as in B. musculus, but that digit IV. comes rather nearer to it 

 in length than in B. musculus. Also that digits II. and V. 

 are short relatively to digits III. and IV., being under half the 

 length, while in B. musculus they attain to about two-thirds of 

 the length of the two long digits. In Megaptera the radial 

 digit II., the index-, contrasts greatly with the ulnar digit V., 

 in the robustness and length of its bones compared with those 

 of B. musculus. With a phalanx less than digit V. it maintains 

 its greater length ; its three bones are not far from twice the 

 length of the corresponding bones of digit V., and are several 

 times their thickness, while in B. musculus the difference in 

 length and in the thickness of the bones of these two digits 

 is not great. The enormous robustness in particular of the 

 metacarpal bone of the radial digit in Megaptera almost reminds 

 one of the metatarsal of the human hallux, having the same 

 adaptation, giving resistance to that side of the limb. 



Number of the Digital Bones. — The number of the bones, 

 including the metacarpal, in each of the four digits, is, — digit 

 II., 3 ; digit III., 8 ; digit IV., 7 (and a cartilage) ; digit V., 4. 

 Beyond these, each digit has the terminal cartilage, those of 

 digits V. and III. with a joint in them, that of digit II. with 

 two successive joints in it. 



The following Table, giving the number of ossified bones, 

 including the metacarpal, found in each finger in my four 

 dissections of B. musculus (all males), shows how the number 

 may vary according to maturity or otherwise. The Table does 

 not give the terminal cartilages, which might subsequently have 

 become ossified. The number in the B. borealis (male), also 

 given in the Table, is the same as in the 50-feet-long B. mus- 

 culus. 



