224 WHALES, PAST AND PRESENT xv 



purpose and mode of action of the limb, reduced to a condition 

 of atrophy verging on complete disappearance. 



The changes that have taken place in the hind-limbs 

 are even more remarkable. In all known Cetacea (unless 

 Platanista be really an exception) a pair of slender bones are 

 found suspended a short distance below the vertebral column, 

 but not attached to it, about the part where the body and the 

 tail join. In museum skeletons these bones are often not 

 seen, as, unless special care has been taken in the preparation, 

 they are apt to get lost. They are, however, of much 

 importance and interest, as their relations to surrounding parts 

 show that they are the rudimentary representatives of the 

 pelvic or hip bones, which in other mammals play such an 

 important part in connecting the hind-limbs with the rest of 

 the skeleton. The pelvic arch is thus almost universally 

 present, but of the limb proper there is, as far as is yet known, 

 not a vestige in any of the large group of toothed whales, not 

 even in the great cachalot or sperm whale, although it should 

 be mentioned that it has never been looked for in that animal 

 with any sort of care. With the whalebone whales, however, 

 at least in some of the species, the case is different. In these 

 animals there are found, attached to the outer and lower side 

 of the pelvic bone, other elements, bony or only cartilaginous 

 as the case may be, clearly representing rudiments of the first, 

 and in some cases the second segment of the limb, the thigh 

 or femur, and the leg or tibia. In the small Baloenoptera 

 rostrata a few thin fragments of cartilage, imbedded in fibrous 

 tissue attached to the side of the pelvic bone, constitute the 

 most rudimentary possible condition of a hind-limb, and could 

 not be recognised as such but for their analogy with other 

 allied cases. In the large rorqual, Balcenoptera musculus, 67 

 feet long, previously spoken of, I was fortunate enough in 

 1865 to find attached by fibrous tissue to the side of the pelvic 

 bone (which was sixteen inches in length) a distinct femur, 

 consisting of a nodule of cartilage of a slightly compressed, 

 irregularly oval form, and not quite one inch and a half in 

 length. Other specimens of the same animal dissected by 

 Van Beneden and Professor Struthers have shown the same ; 

 in one case, partial ossification had taken place. In the genus 



