1883.] on WhaleSy Past and Present, and their ProhaUe Origin, 11 



freely movable at the shoulder-joint, where the humerus or upper- 

 arm bone articulates with the shoulder-blade in the usual manner, 

 but beyond this point, except a slight flexibility and elasticity, there is 

 no motion between the different segments. The bones are all there, 

 corresponding in number and general relations with those of the 

 human or any other mammalian arm, but they are flattened out, and 

 their contiguous ends, instead of presenting hinge-like joints, come in 

 contact by fl^^ surfaces, united together by strong ligamentous bands, 

 and all wrapped up in an undivided covering of skin, which allows 

 externally of no sign of the separate and many-jointed fingers seen in 

 the skeleton. 



Up to the year 1865 it was generally thought that there was 

 nothing to be found between this bony framework and the covering 

 skin, with its inner layer of blubber, except dense fibrous tissue, 

 with blood-vessels and nerves sufficient to maintain its vitality. 

 Dissecting a large Korqual, 67 feet in length, upon the beach of 

 Pevensey Bay in that year, I was surprised to find lying upon the 

 bones of the fore-arm well-developed muscles, the red fibres of which 

 reached nearly to the lower end of these bones, ending in strong 

 tendons, passing to, and radiating out on, the palmar surface of the 

 hand. Circumstances then prevented me following out the details 

 of their arrangement and distribution, but not long afterwards Pro- 

 fessor Struthers, of Aberdeen, had an opportunity of carefully dis- 

 secting the fore-limb of another whale of the same species, and he 

 has recorded and figured his observations in the ' Journal of Anatomy ' 

 for November 1871. He found on the internal or palmar aspect of 

 the limb three distinct muscles corresponding in attachments to the 

 flexor carpi ulnaris, the flexor profundus digitorum, and the flexor 

 longus pollicis of man, and on the opposite side but one, the extensor 

 communis digitorum.* Large as these muscles actually are, yet, 

 compared with the size of the animal, they cannot but be regarded as 

 rudimentary, and being attached to bones without regular joints and 

 firmly held together by unyielding tissues, their functions must be 

 reduced almost to nothing. But rudimentary as the muscles of the 

 Fin-whales are, lower stages of degradation of the same structures are 

 found in other members of the group. In some they are indeed 

 present in form, but their muscular structure is gone, and they are 

 reduced in most of the toothed whales to mere fibrous bands, scarcely 

 distinguishable from the surrounding tissue which connects the inner 

 surface of the skin with the bone. It is impossible to contemplate 

 these structures without having the conviction forced home that here 

 are the remains of parts once of use to their possessor, now, owing to 

 the complete change of purpose and mode of action of the limb, reduced 

 to a condition of atrophy verging on complete disappearance. 



The changes that have taken place in the hind-limbs are even 



* The muscles of the fore-arm of an allied species, Balcenoptera rostrata, were 

 described by Macalister in 1868, and Perrin in 1870. 



