OSTEOLOGY OP THE PIGMY WHALE. 97 



curved ; the next four (PI. IX. figs. 4, 5) are sharply bent at right angles at a point 

 some distance from the capitulum. The bending in the last of these is not so marked. 

 It more approaches the regular curve of the succeeding ribs. In the ribs further 

 towards the end of the series (PI. IX. fig. 7) the curvature is less and less marked, and 

 the rudimentary last rib is almost quite flat. At the angle where the rib bends down 

 it is flat and compressed, as if the bone had been squeezed between the thumb and first 

 finger. This sharpish edge is recognizable on ribs three to five inclusive, and even to 

 a trifling extent in number six. The anterior set of ribs are moderately flattened in a 

 plane at right angles to the long axis of the body. 



The last of the series are much more flattened, but in a plane parallel to that axis. 

 The intermediate ribs have a twist about one fourth of the way down ; the distal 

 portion of the rib gets to be expanded in a plane parallel with the long axis of the 

 body, while the head end retains its parallelism to axes at right angles to the long 

 axis of the body. This twist is gradually rectified as we progress from the anterior 

 to the posterior ribs. 



The peculiar form of the first rib has been mentioned. The six following ribs are 

 narrow in diameter. The eighth has a greatest diameter of 3:^ inches ; the greatest 

 breadth is attained by the tenth, which is some 5J inches in diameter. This is 

 maintained through the next four, after which the breadth diminishes and the small 

 last rib is very narrow, and indeed altogether rudimentary. The very dift'erent 

 appearance of ribs from diff'erent regions is illustrated in the accompanying drawings 

 (PI. IX. figs. 4-7). None of the ribs reach the bodies of their vertebrae, a feature in 

 which of course Neobalaina agrees with other Mystacoceti. But several of them have 

 a distinct capitulum and tuberculum with an intervening neck. In the first rib these 

 could barely be distinguished. Ribs 2-6 have both capitulum and tuberculum quite 

 plain ; these are most obvious, because separated by a longer neck, in vertebrae 3 and 

 4 (PL IX. figs. 4, 6) ; in them the neck measured about 6 inches in length. 



Another feature which the ribs of this whale share with those of other Whalebone 

 Whales should be noticed. In the posterior and more rudimentary bones of the series 

 the rib gradually decreases in diameter, not only at the distal free end, but also at 

 that end which is nearest to the vertebral column. It does not appear, indeed, that 

 during life the thin commencement of many of the posterior ribs ever came into direct 

 relations with the vertebral column. It is, in fact, the middle part of the rib which is 

 alone ossified, the two ends having apparently been represented by fibrous or 

 cartilaginous tissue. 



The great breadth and the large number of the ribs of Neohalcena give a suggestion 

 of a Sirenian to this, as I believe, primitive form of Whalebone Whale. The likeness 

 is here only pointed out ; it is not possible to build any views as to the afiinities of the 

 Cetacea upon it. 



In the introductory anatomical sketch of their great work on the Osteology of 



p2 



