34 
partially than the mammalian tribes. The bones 
that cross immediately behind the head, constituting 
arches, below and behind those formed by the lower 
jaw and lingual bones, are not alone bones that cor- 
respond to the collar bone, and clavicle of mammalia, 
but to those of the merry-thought, or furcula proper 
to birds. In this respect, if we classified by the 
doctrine that raises the animal to a higher series 
and degrades it to a lower, according as the bony 
structure is more or less developed, fishes would 
stand in a higher range of life than mammifcrous 
animals, for in them there is no corracoid bone or 
furcula, or only the rudimentary traces of it in the 
eorracoid process, while in the hoofed quadruped the . 
clavicle or collar bone, is altogether wanting. So 
far it may be truly said, the fish-nature exhibits a 
higher development; but, we no sooner quit these 
bones to trace the representative hand in the pectoral 
fin than we find them as much behind in structure, 
as they seemed in advance, by the possession of the 
clavicle and the furcala. When we look for the arm 
bone or humerus, we find it quite radimentary. The 
two bones of the fore-arm seem represented by no 
interposing bone. 'The shoulder-joint and elbow- 
joint are in general almost one and the same. ‘¢ The 
two bones of the fore-arm, the ulna and raduus are, 
in some few fishes only, so constructed as to roll with 
tolerable freedom on each ether, exactly in the same 
way as they roll on each other in man, in the action 
of rotating the hand. It is by this means they have 
the power of changing the direction of the flat part 
of their pectoral fin, during its play in the water, a 
