272 THE MAN US. [chap. 



by interposed tracts of fibrous tissue, without any synovial 



\ joints. Nodules of bone are deposited in the centre of 



some of these cartilaginous masses, and slowly reach the 



surface as the animal attains maturity : there are commonly 



not more than five such ossifications. The phalanges 



\ appear like cylindrical or slightly flattened bony masses, 



; with roughly truncated ends, set in a continuous rod of 



J cartilage. In this way a certain amount of flexibility and 



elasticity is secured in the flipper, but beyond this there 



is no actual motion between the various bones of which 



' it is composed. 



The manus of the Right Whale (Balcena mysticetus) is 

 comparatively short and very broad, having all five digits 

 present, and being also extended on the ulnar side by a 

 flattened cartilage projecting from the edge of the carpus, 

 probably representing the pisiform bone. In an adult speci- 

 men there are only three distinct ossifications in the carpus. 

 The numbers in the digits are respectively I. I, II. 4, III. 5, 

 IV. 4, and V. 3. In the Rorquals (Balanoptera) the first digit 

 is absent, and the manus is of an extremely elongated and 

 narrow form. The carpus has five ossifications, and the 

 number of phalanges varies somewhat in different species. 



In the Odontocetes, the ossification of the skeleton of 

 the manus is usually more complete than in the Whalebone 

 Whales, the carpal bones generally coming in close contact 

 at their edges, and assuming a somewhat polygonal form. 

 The phalanges are also better ossified, often having epi- 

 physes at each extremity, and they are connected together 

 by imperfect synovial joints. They are always very much 

 flattened, and their extremities being truncated and their 

 sides nearly parallel, they are either square or oblong 

 in form. In size they gradually decrease to the end of 

 the digit, the last often consisting of minute nodules or 



