EVOLUTION AND EXTERNAL APPEARANCE 



59 



Figure 21. Comparison of the body shape and skeleton of a Blue Whale and a horse. Note the 



dijference in the development of limbs, neck, and tail, and the presence of chevron bones on the 



lower side of the Blue Whalers caudal vertebrae. 



The longer bone makes up the entire Cetacean pelvis, but unlike the 

 pelvis of normal mammals it is not attached to the vertebral column, 

 though, in the males, the penis has remained anchored to the bone. The 

 smaller bone which is generally just over an inch in length and which is 

 sometimes fused with the larger, may be thought of as a vestigial femur 

 (Fig. 227). In some Right Whales, e.g. the Greenland and the Biscayan, 

 another small bone, representing the tibia, is attached to the femur. 

 Occasionally a tibia is also found in Sperm Whales. Thus, at Ayukawa 

 Whaling Station (Japan), a Sperm Whale was brought in in 1956, with 

 a 5-inch tibia projecting into a 5i-inch external 'bump', and a Russian 

 factory ship in the Bering Sea had a similar experience in 1959. All other 

 Odontocetes have only single pelvic bones. Moreover, in some species. 



Figure 22. Left view of left pelvic bone of a male Sperm Whale with vestigial femur fused to it. 

 The animal was found stranded in Holland {Texel) on gthjuly ig^o. {Van Deinse, ig54.) 



