118 PROFESSOR STRUTHERS. 



their tips, the convergence in B. musculus is from 9 inches at 

 the roots to 2| inches at the tips ; in Megaptera from 7 inches 

 at the roots to 4 inches at the tips. The ends are not in con- 

 tact, separated by intervals of from i to J inch, but are nearer 

 each other than are the processes of B. musculus at the same 

 distance from the bodies. The process of the 5th, as in B. 

 musculus, is the central one to which the others converge, but 

 the 6th and 7th have not so much forward slope as in B. 

 musculus. 



In form the distinction between the nerve-groove stage and 

 tubercular stage is scarcely recognisable. The whole process is 

 more rounded than in B. musculus, standing out like a long 

 finger, but is still somewhat flattened, surfaces forwards and 

 backwards, especially towards the root. The greater breadth 

 and flatness of the superior as well as of the inferior processes 

 in B. nmsculus may be regarded as related to their having to 

 support large terminal plates. The special roughnesses seen 

 in B. musculus for the attachment of the superior intertrans- 

 verse ligament, are but faintly marked in Megaptera. All this 

 points to less necessity for binding together of the vertebrae of 

 the neck in Megaptera. Although these superior processes 

 might bear a ligament of considerable strength, Megaptera 

 wants the binding of the enormously strong external inter- 

 transverse ligaments {loc. cit, 1872, p. 9) which hold together, 

 at the apex of the pyramid, the expanded terminal plates, and 

 tie them to the vast expansion of the wing of the axis. 



Comparing the superior processes with each other, the 3rd 

 is the most slender in both Megaptera and B. musculus, but 

 more strikingly so in Megaptera. In B. musculus they increase 

 moderately in strength backwards from the 3rd to the 5th, and 

 then greatly on the 6 th and 7 th. In Megaptera that progres- 

 sion is interrupted by the 4th process being as thick as the 5th 

 on the left side, and much thicker than it on the right side. 

 The 6th has the same robustness as the right 4th. The 7th 

 undergoes very sudden enlargement, and, relatively to the others 

 and to the 1st dorsal, is larger than in B. musculus. It is 

 almost, if not quite, as large as the 1st dorsal, and presents 

 almost as large and as thick an outer end. The 7th stands out 

 as a strong process, and in the recess between it and the axis 



