APPENDIX. 5£5 



Their form somewhat resembles what takes 

 place in the quadruped, at least in those of which 

 the uses are similar, as the vertebrie, ribs, and 

 bones of the anterior extremities have their arti- 

 culations in part alike, although not in all of 

 them. The articulation of the lower jaw, of the 

 carpus, metacarpus, and fingers, are exceptions. 

 The articulation of the lower jaw is not by simple 

 contact either single or double, joined by a cap- 

 sular ligament, as in the quadruped ; but by a 

 very thick intermediate substance of the liga- 

 mentous kind, so interwoven that its parts move 

 on each other, in the interstices of which is an oil. 

 This thick matted substance may answer the same 

 purpose as the double joint in the quadruped. 



The two fins are analogous to the anterior ex- 

 tremities of the quadruped, and are also some- 

 Y/hat similar in construction. A fin is composed 

 of a scapula, os humeri, ulna, radius, carpus, and 

 metacarpus, in which last may be included the 

 fingers, because the number of bones are those 

 which might be called fingers, though they are 

 not separated, but included in one general cover- 

 ing with the metacarpus. They have nothing 

 analogous to the thumb, and the number of bones 

 in each is different : in the fore-finger there are 

 five bones ; in the middle and ring-finger seven, 

 and in the little finger four. The articulation of 

 the carpus, metacarpus, and fingers, is different 

 from that of the quadruped, not being by capsu- 

 lar ligament, but by intermediate cartilages con- 

 nected to each bone. These cartilages between the 



