86 PROFESSOR STRUTHERS. 



lumbar and two first caudal, the top of the articular processes 

 falls nearly 1 inch compared with those in front ; behind this 

 they again rise in height. After the next last lumbar, the 

 posterior border of the process becomes concave backwards, and 

 this with the diminishing obliquity of the anterior border gives 

 the processes, after the 2nd caudal, a straight-up direction, the 

 process increasing somewhat in breadth upwards. 



In thickness the processes undergo sudden increase at the 

 unfinished top, from \ inch on the last lumbar to 1 inch on the 

 1st caudal, and to 1 J inch on the 5th caudal at its middle ; 

 after which they diminish, but are still 1 inch thick on the 

 10th, the last vertebra with a complete neural arch. On the 

 next four vertebrae (llth to 14th) the low ridges, perforated 

 by the passage above noted, represent pedicle and articular 

 processes combined. 



The greater width-apart of the articular processes in Megap- 

 tera, compared with B. musculus, is at once seen in surveying 

 the series from the atlantal or the caudal end. Taking the 

 measurement at the fore part of the processes, inner edge, the 

 distance falls from the 1st to the last dorsal from 11 J inches 

 to 4J ; at the 5th and 6th lumbar it is 4 inches ; at 9th lumbar, 

 3|- ; at 1st caudal, 2J ; at 8th caudal, If ; at the 10th caudal, 1J. 

 The measurements are given in full in Table II. The measure- 

 ments of a process at the posterior dorsal or anterior lumbar 

 region are height, 3| inches; length, 3; thickness, at the un- 

 finished top, f inch, at the middle, f to 1 inch. The anterior 

 border, and anterior part of the lower border, are much thinner, 

 giving the process a wedge shape. 



[Great Anterior Articular Processes in B. musculus. 



In B. musculus the decidedly quadrate form is seen from the 7th 

 dorsal to the 1st lumbar. In front of the 7th dorsal, the upper 

 anterior angle rapidly disappears, reducing the process to a narrow 

 triangular projection, which, on the three first dorsal, is some distance 

 external to the articular surface. The quadrate form, as compared 

 with the form in Megaptera, is obtained by the development of the 

 anterior-inferior and posterior-superior corners. The inferior-anterior 

 forms almost a right angle, but a little rounded off. The measure- 

 ments at the 14th dorsal are height, 4^ inches; length, 4^; thick- 

 ness at the top, f, at the middle, the same. The thinness of the 

 processes is remarkable compared with those of Megaptera. The 



