J. D. Dana on Cephalization, _ : 3 
of decephalization, by the reverse,) occur in the two highest sub- 
kingdoms, those of Vertebrates and Articulates. They fail in the 
two lower subkingdoms, those of Mollusks and alse because 
of the absence of the gg om structure for showing it 
he examples under Vertebrates and Articulates, and the rela- 
tions of the orders among Molluske, may be briefly considered. 
ble, owing to the fixed nature and simplicity of the head, and 
4 also the limited number of feet, two igen being the maximum. 
Mammals. In passing downward from the exalted position 
which Man holds, there is a transfer of the fore-limbs to the 
locomotive series: the structure of the head in Vertebrates, even 
to the lowest Fishes, admits of no other case of analogous trans- 
fer.” In the Walrus, the tusks have some locomotive a 
as they serve to rest the fore-part of the animal or i 
the ice, while the body is in the water; but this is an cena 
under the second method. The feet are wholly absent in Snakes, 
and the ribs aid in locomotion; but this is only a degradation 
of the vertebrate type, and not dectohidication by the firs 
method. In most /ishes, and in Whales, the locomotive fine 
tion is transferred mainly to the elongated vertebrated posterior 
Sires of the body—a case of degenerative degradation, simi- 
_ iar to the last, and analogous also to the muliiphicative 
It is of sufficient interest in this connection to be re ated 
posterior thoracic 
_ such appendages exist in the secondary type embrac Feces the species), 
_ “These circumstances, moreover, are “independent of a St ree of intelli 
gence, by an extension of "the sphere of growth beyond the proper limits of the 
sphere of activity.” 
? To the zoologie al characteristics of Man, mentioned in the writer’s article on 
- Mammals,—that is, the extreme cephaliza’ ization of his system and the erect form con- 
_ nected therewith,—should be added the following, se while 4 pe 
in 
Prof. Huxley—is of small importance in this conne 
The writer's view of aracteris 
ties af Nba geal celta iitrsecad ial ae 
are given in the last volume of this Journal, on page 452. 
