xvi.] CETACEA. 301 



The determination of the homologies of the carpal bones 

 of the Cetacea with those of other Mammalia is beset with 

 difficulties, and has consequently led to some differences 

 of opinion among those anatomists who have attempted it. 

 Moreover every species appears liable to certain individual 

 variations, and sometimes the different sides of the same 

 animal are not precisely alike, either in the arrangement, or 

 even the number of the carpal ossifications. 



The pisiform is occasionally represented by a small ossifi- 

 cation on the ulnar border of the carpus. Excluding the 

 above, the carpus of the Odontocetes appears rarely to con- 

 sist of more than six bones, three belonging to the proximal 

 and three to the distal row. 1 



The three bones of the proximal row are constant, and 

 may easily be identified as corresponding to the scaphoid, 

 lunar and cuneiform of human anatomy, or the radiate, in- 

 termedium, and ulnare of Gegenbaur. The middle one is 

 usually the largest and most thoroughly ossified. 



The three bones of the distal row are generally represented 

 by distinct ossifications (corresponding apparently with the 

 trapezoid, magnum, and unciform) in the genera Hyperoodon, 

 Mesoplodon, Beluga, and Monodon. 



In many cases (see Fig. 105) the bones of the distal row 

 of the carpus are reduced to two, which appear to corre- 

 spond best with the trapezoid and unciform, the magnum 

 being either absent or amalgamated with the trapezoid. 2 



The trapezium appears never to be present as a distinct 



1 At the meeting of the British Association in 1885, Prof. Turner 

 exhibited the carpus of a Hyperoodon with five distinct bones in the 

 distal row. See " Journ. Anatomy and Physiology," October, 1885. 



8 For the reasons for this determination (about which, however, 

 there is considerable doubt), see Flower, " On the Osteology of the 

 Sperm Whale " ; Trans. Zoological Society, vol. vi. p. 360. 



