18 



PROFESSOR STRUTHERS. 



PART II. 



THE LIMBS. 



Pectoral Fin. 



1. Proportions and Form, .. 18 



2. Table I. Measurements 



of Pectoral Fin and its 

 Parts,. ... 20 



3. Scapula, . . .21 



4. Table II. Measurements 



of the Scapula, . . 22 



5. Humerus, . . .27 



6. Fore-arm, . . .27 



7. Elbow-Joint, . . 29 



8. Carpus,. . .30 



9. Cartilages and Joints of 



the Digits, ... 32 



10. Bones of the Digits, . 36 



11. Table III. Number of 



the Digital Bones, . 37 



Page 



1 2. Table IV. Measurements 



of the Digital Bones, . 38 



13. Proportion of Cartilage 



to Bone, . . .43 



14. Adaptations of the Nodes 



and Phalanges, . . 43 



15. Muscles of the Fore-arm 



and Fingers, . . 46 

 B. Rudimentary Hind Limb. 



16. Table V. Measurements 



of the Pelvic Bone and 

 Femur, . . . f)0 



17. Pelvic Bone, . .50 



18. Femur, . . . .51 



19. Ligaments and Muscles, 52 



20. Function, ... 59 



21. Explanation of the Plates, 59 



(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 3J (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 



