xv HIND-LIMBS 225 



Megaptera a similar femur has been described by Eschricht ; 

 and the observations of Eeinhardt have shown that the 

 Greenland right whale (Balcena mysticetus) has not only a 

 representative of the femur developed far more completely 

 than in the rorqual, being from six to eight inches in length 

 and completely ossified, but also a second smaller and 

 more irregularly formed bone, representing the tibia. Our 

 knowledge of these parts in this species has recently been 

 greatly extended by the researches of Dr. Struthers, who has 

 published in the Journal of Anatomy for 1881 a most careful 

 and detailed account of the dissection of several specimens, 

 showing the amount of variation to which these bones (as 

 with most rudimentary structures) are liable in different 

 individuals, and describing for the first time their distinct 

 articulation one with the other by synovial joints and capsular 

 ligaments, and also the most remarkable and unlooked-for 

 presence of muscles passing from one bone to the other, 

 representing the adductors and flexors of mammals with 

 completely developed limbs, but so situated that it is almost 

 impossible to conceive that they can be of any use ; the whole 

 limb, such as it is, being buried deep below the surface, where 

 any movement, except of the most limited kind, must be 

 impossible. Indeed, that the movement is very limited and of 

 no particular importance to the animal was shown by the fact 

 that in two out of eleven whales dissected the hip-joint was 

 firmly anchylosed (or < fixed by bony union), though without 

 any trace of disease. In the words of Dr. Struthers, " Nothing 

 can be imagined more useless to the animal than rudiments of 

 hind-legs entirely buried beneath the skin of a whale, so that 

 one is inclined to suspect that these structures must admit 

 of some other interpretation. Yet, approaching the inquiry 

 with the most sceptical determination, one cannot help being 

 convinced, as the dissection goes on, that these rudiments 

 really are femur and tibia. The functional point of view 

 fails to account for their presence. Altogether they present 

 for contemplation a most interesting instance of those 

 significant parts, rudimentary structures." 



We have here a case in which it is not difficult to answer 

 the question before alluded to, often asked with regard to 



Q 



