68 



PROFESSOR STRUTHERS. 



less ; the greatest height (lOj inches) b}'' the 2nd, 3rd, 4th, and 

 5th ; the greatest length (8f inches) by the last lumbar and 

 two first caudal, the 3rd and 4th only ^ inch less. An eighth 

 of an inch in such measurements may be only incidental. Thus 

 the 2nd caudal has the greatest size in all directions — breadth 

 11 inches, height 10|, length 8f ; and the 3rd and 4th are 

 scarcely less ; the 1st only a little less. 



From this region the bodies diminish forwards and backwards. 

 In the diminution backwards the height and breadth keep about 

 the same proportion in the first half of the caudal region, and 

 in the last half are more nearly equal. The length remains less 

 than the height or breadth until the fourth last caudal is 

 reached. In the diminution forwards, the decrease in breadth 

 is not great — about 1 inch along the lumbar region (10§ to 9f ) ; 

 along the dorsal region, 1 inch at the 3rd dorsal (9 inches), and 

 at the 1st dorsal |-inch more (to 8|-inches), a total diminution 

 of about 2^ inches from the greatest breadth. In height the 

 diminution goes on gradually, from the 10^ inches on the 2nd 

 caudal, to 7 inches at the middle of the dorsal region, and 

 remains at this on to the 1st dorsal, a total diminution of 3j 

 inches. In length the diminution is great — from the 8f inches 

 of the 10th lumbar, it has fallen to 6f on the last dorsal, and to 

 only 2f on the first dorsal. On the posterior half of the dorsal 

 region it is only 1 inch. On the anterior half it is more rapid, 

 from 5 1 inches to 2f, being fully one-half The shortening of 

 the bodies backwards from the great vertebrae is much more 

 rapid than forwards, the length of the l7th and 18th caudal being 

 about equal to that of the 1st dorsal, a distance backwards of 

 10^ feet (including 15 to 16 vertebraB, from the 2nd caudal), 

 and forwards a distance of 13i feet (including 23 vertebrae, from 

 the 10th lumbar to the 1st dorsal). 



The shortness of the bodies is seen when they lie alongside 

 those of the other finners. The following are the measurements 

 in inches, of the 13th dorsal in the three : — 



