88 PROFESSOR STRUTHERS. 



running to the border of the spinous process, the other leaving 

 that line at about opposite the middle of the great articular 

 process, and going vertically down; and there is a roughness 

 where the two lines separate. Arrived at the 9th lumbar, the 

 vertical line is more distinct, and on the four vertebra behind 

 rises into the internal articular process above described. Be- 

 tween these two lines, as we go back along the dorsal and 

 lumbar regions, the bone is smooth, facet-like, but not as if it 

 had supported cartilage. The facet, scarcely excavated, is 

 square-shaped along the dorsal region, is about 2 inches verti- 

 cally by 1 J inch, and along the lumbar region becomes gradu- 

 ally triangular and smaller. On the 10th lumbar it is in front 

 of the lesser process and mostly higher up. Where these lesser 

 processes are present, though in a rudimentary state, the pos- 

 terior articular processes are undergoing modification, and the 

 great anterior processes on the 10th lumbar and first two caudal 

 are lower than on the vertebra before and behind them. 



The mode of breaking up of the anterior border of the 

 spinous process is characteristic in Megaptera. The bifurca- 

 tion of the very sharp ridge of the border takes place high up. 

 It is seen to take place a long way behind the articular pro- 

 cesses until we go back to the 8th lumbar, when that relation 

 begins to be reversed. But this is mainly owing to the length 

 and obliquity of the lamina, which decrease backwards in the 

 lumbar region. The actual early bifurcation is seen by the 

 height of the wide triangular concave area from it down to the 

 level of the roof of the neural canal, 2 J to 3 inches, while in B. 

 musculus it is scarcely half that height, and is greatly narrower 

 from the presence of the lower articular processes. 



[Internal Anterior Articular Processes in B. musculus. 



In B. musculus these processes are present from the 6th dorsal to the 

 14th lumbar, with traces farther back. The 5th dorsal is the most pos- 

 terior of the vertebrae presenting an articular socket. Going back- 

 wards, it is seen that the internal, or minor, articular process is serial 

 with the inner edge of the socket of the 5th dorsal. Increasing 

 rapidly, it is fully developed from the 10th dorsal to the 10th or 

 llth lumbar. In its full size it is a triangular flattened process, 

 projecting J to f inch with a base 1^ inch in height, pointed and 

 sharp-edged, and about J inch thick at the middle. The median 

 fossa between the minor processes contracts very much as we go back 



