THE PROGRESS OF DEGRADATION. 171 



I am aware that by some very distinguished comparative 

 anatomists, among the rest Professor Owen, the attachment, 

 so common among fishes, of the scapular arch and the fore 

 limbs to the occipital bone is regarded, not as a displacement, 

 but as a normal and primary condition of the parts.* Kecog- 

 nising in the scapular bones the ribs of the occipital centrum^ 

 the anatomists of this school of course consider them, when 

 found articulated to the occiput, as in their proper and ori- 

 ginal place, and as in a state of natural dislocation when re- 

 moved, as in all the reptiles, birds, and mammals, farther 

 down. We find Professor Oken borrowing support to his hy- 

 pothesis from this view. The limbs, he tells us, are simply 

 ribs, that in the course of ages have been set free, and have 

 become by development what they now are. And it is un- 

 questionably a curious and interesting fact, that there are cer- 

 tain animals, such as the crocodile, in which every centrum 

 of the vertebral column, and of every vertebra of the head, 

 has its ribs or rib-like appendages, with the exception of the 

 occipital centrum. And it is another equally curious fact, 

 that there is another certain class of animals, such as the 

 osseous horn-covered fishes, with the Sturionidse, Salaman- 

 droidei, and at least one genus among the placoids (the Chi- 

 mseroidei), in which this occipital centrum bears as its ribs 

 the scapular bones, with their appendages the fore limbs. It 

 is the centrum without rihs that is selected in these animals 

 as the centrum to which the scapular ribs should be attached. 

 Be it remembered, however, that while it is unquestionably 

 the part of the comparative anatomist to determine the rela- 

 tions and homologies of those parts of which all animals are 

 composed, and to interpret the significancy in the scale of 

 being of the various modes and forms in which they exist, it 



* The geological ground must for the present be abandoned by those 

 who do not adopt the views of Oken. Their reasoning must be based on 

 grounds similar to those reco^ised as sutScient by Agassiz.— L. M. 



