ANATOMY OF MEGAPTERA LONGIMANA. 117 



That of the fourth vertebra is shorter than the third by f inch, 

 and is more robust throughout, especially vertically, giving it a 

 more rounded form. The tubercular stage is seen on its outer 

 third. Viewed from below, the inferior processes stand out 

 transversely. Viewed from the side, they are seen to be directed 

 considerably more downwards than are the corresponding parts 

 of the same vertebrae of B. musculus. The shortness of the 

 inferior transverse processes in Megaptera, and their cessation 

 after the 4th vertebra, indicate a much less development of the 

 inferior intertransverse ligament in Megaptera than in B. 

 musculus. 



[In this 50-feet-long B. musculus the inferior processes of the 3rd, 

 4th, and 5th vertebrae show the root stage, tubercular stage, and 

 nerve-groove stage (described loc. cit., 1872, pp. 6 and 25), and the as 

 yet incomplete terminal plate. The process of the 5th is, as in the 

 other specimens, the strongest. The processes of the 6th show the 

 tubercular stage, 2| to 3 inches in length, beginning by a forward 

 angular projection, and tapering outwards to a blunt point. The 7th 

 vertebra shows only the low tubercle on the posterior half of the 

 body.] 



Superior Transverse Processes. These differ from the trans- 

 verse processes of B. musculus in commencement, length, direc- 

 tion, form, and in the absence of marked division into stages. 

 The commencement of the process in Megaptera is more external 

 on its upper margin than on its lower ; in B. musculus it is the 

 reverse to a marked extent. This is owing to the more outward 

 position of the articular processes in Megaptera. On their lower 

 margin the processes begin external to the plane of the side 

 of the bodies (J to 1 inch, increasing backwards), owing to the 

 narrowness of the bodies and the greater length and obliquity 

 of the pedicle than in B. musculus. In the latter the lower 

 margin of the process begins internal to the plane of the side of 

 the body on the third and 4th vertebra, but not when the 6th 

 and 7th are reached. 



In length these five processes differ but little from each other 

 (see Table V.). They have all had cartilage on the end, and 

 terminate in blunt rounded ends. In direction their compara- 

 tive shortness lessens the appearance of great convergence pre- 

 sented by B. musculus. Taking the distance between the 

 processes from the 7th to the axis, at their roots and at 



