18 



PROFESSOR STRUTHERS. 



(A) The Pectoral Fin. 



1. Proportions and Form. — The measurements given in 

 Table I. below show that the greater length of the paddle in 

 Megaptera is obtained mainly in the digital part. In B. 

 musculus the digital part is shorter than the arm and fore-arm 

 together, in the proportion of about 2 to 3| (2 feet 1^ inch 

 against 3 feet 7 inches). In Megaptera the proportions are 

 reversed, the digital part being to the arm and fore-arm together 

 as about 5 to 7 (4 feet 10 inches against 6 feet 9 inches). The 

 measurements in the Table show that the greater actual length 

 of the arm and fore-arm in Megaptera than in B. musculus is 

 contributed in about equal proportion by the arm and fore-arm. 

 These proportions are seen by comparing figures 6 and 13, 

 of the same length, the former that of Megaptera, reduced to 



