326 Dana on the Classification of Animals 
method may arise from a self-subdivision of enlarging normal 
segments, or from additions beyond the range of the normal 
number. The many joints of the antenne in Crustaceans of the 
Cyclops group, the writer has shown to result through the former 
method, and the multiple segments of Phyllopods may be of the 
same origin: but there are no facts yet ascertained that would 
refer the multiplication of segments in Myriapods and Worms to 
this method. 
Viewed on the ascending grade, this method is the limitative. 
D. STRUCTURAL. 
7. Analytic—Exhibited in a resolving of the body-structure, 
or of an organ, more or less completely, into its equal normal 
elements, or in a tendency to such a resolution. 
A relaxed state of the cephalic power leads to a relaxed and 
elementally-constituted structure. When this method charac- 
terizes strongly the general structure, the form is usually degra- 
ational; as in riapods, Worms, larves of. Insects,—these 
normal elements of an Articulate,) without a subdivision into 
head, thorax and abdomen. Fishes, of 
thorax has 3 to 5 times the bulk of the head ;—showing 4 con- 
densation in the head-part equal to 6 to 10 times that of the 
thorax. Concentration in an animal structure is therefore em! 
nently cephalic concentration, or, in a word, cephalization,—the 
head being the part most condensed, and least liable to occur 
resolved into its elements. een 
Ang fae method, viewed on the ascending grade, is the = 
8. Simplificative—Exhibited in increased simplicity of stra’ 
ture, and in an equality of parts that are normally identical. 
The cases are— 3 we 
_ a. Simplicity from diminished number of internal or external ! 
