PALZONTOGENY AND PHYLOGENY S11 
the paleontologist can correlate correctly fossil beds where even 
all the genera and species are new; he can even prophesy con- 
cerning the occurrence of unknown genera in certain horizons 
when he finds their minute counterparts in youthful stages of 
later forms; infact he could often furnish just as exact a descrip- 
tion of the form as if he had the adult genus before him. 
NOMENCLATURE OF STAGES OF GROWTH. 
In order to correlate ontogenetic stages with the generic 
changes seen in the development of the race it is necessary to 
have an exact scientific nomenclature. The most satisfactory is 
that given by Professor Hyatt in ‘‘Phylogeny of an Acquired 
Characteristic.’’? 
TABLE OF ONTOGENETIC STAGES. 
Stages Stages Substages Comparison with phylogeny 
Embryonic (1) Embryonic Protembryo | 
Mesembryo | 
Metembryo | 
Phylembryonic | 
Neoembryo [ 
Typembryo | 
Phylembryo } 
Epacme 
| 
Larval (2) Nepionic Ananepionic ( 
Metanepionic + Phylonepionic 
:) 
lL 
Paranepionic 
Adolescent (3) Neanic } Ananeanic 
t 
t 
Metaneanic Phyloneanic 
Paraneanic 
Adult (4) Ephebic Anephebic 
Metephebic Phylephebic 
Parephebic 
Acme 
Senile (5) Gerontic Anagerontic 
Metagerontic + Phylogerontic 
Paragerontic 
Parac- 
me 
With the embryonic stage the paleontologist can do noth- 
ing, except the very last substage or phylembryo, when the 
Mollusca, Brachiopoda and other groups begin to secrete their 
shells; but all the later stages are easily accessible in well- 
preserved material. 
* Proc, Am. Phil. Soc., Vol. XXXII, No. 143, pp. 391 and 397. 
