96 
[April 5, 
use of tlio term " e]»eiiil)iToni(; staui's," iiiid this li;is already been 
found useful above. It only remains to add tiiat the same prefix 
is also useful in desioiiating the exclusion of other stages, tlius one 
can speak also of the " epinepionic " or " epineanic " stages in 
this same way without danger of confusion with any other term.^ 
It is often possible to employ a naore si>ecific and characteristic 
designation than epembryonic. Tlius, among shell-bearing forn)S 
one can distinguish between the embryonic shell and the true shell ; 
for example, the proteguluni and the tegulum of Brachiopoda as 
defined by Beecher, the prodissoconch and the dissoconch of 
Pelecypoda as defined by Jackson, the periconch and conch of 
Scaphopoda, the protoconch and conch of Cephalopoda. In all of 
these forms it is practicable to speak of tegular, dissoconchial, or 
conchial stages or periods, meaning thereby all of the epeud^ry- 
onic stages of these types. 
Haeckel in liis " Morphologic der organismen " sketched the 
physiology of ontogeny and phylogeny and gave the general 
correlations of the two series of phenomena, together with an 
appropriate nomenclature which has been here adopted with some 
necessary changes. 
The dynamical relations of three great phases of evolution in 
the phylum were designated by Haeckel "^ as the epacme, including 
the rise of the type from its origin, the acme, meaning the period 
of its greatest expansion in members and forms, and t\\e par acme, 
or decline towards extinction, and these phenomena were correlated 
with the similar physiological phenomena of the ontogeny, and 
these appear in the table of phyletic terms given below. 
Previous to this in the same volume, page 76, Haeckel gives his 
classification of the develo|>niont of the individuid under three 
headings: "Anaplasis oder aufbildung (evoluti(^)," meaning 
thereby to include the physiological phenomena of all of the stages 
developed in the four earlier stages of the individual. This is 
certainly a useful term for the entire series of transformations 
from the fertilization of the ovum until the progressive stages are 
all passe<l through. It <loes not express nor can it be used for 
1 Post-emhryoiiic is in use fur tlie yoiuig stages among- embryologists, and is equiv- 
alent to tiie term nepionie, Init it is not consistent with tlie other terms of bioplastology. 
and is a iiyhrid. 
•2 ^[orpliologie der orgiinismen, v. 2, p. :J2()-36(;. 
