Hyatt.] 
94 [April 
T:il)le ir, printed below, is therefore made np of terms wliieli 
are substantially the same as those suggested by Buckman and 
Bather, and in it I have also followed a suggestion kindly sent me 
by letter from JNIr. Buckman, in adopting the prefixes "ana," 
"meta," or "para" for the designation of the substages of dev^elop- 
ment. This has the great advantage of adding to the means 'of 
expressing observations accurately, quite as well as by the use of 
an entirel}^ distinct word, and at the same time preserves in each 
term a direct reference to the stage to which it belongs. Thus 
one can speak of the metanepionic or ananeanic substage without 
referring to the stages in which they occur, and yet the reader 
will at once recognize to what stages they sliould be referred. [ 
Ontogeny, Table (II). 
Conditions. Stayrs. Stages. Substayes. Sitbstayes. 
Embryonic. 1 Embryonic. Several.' No popular names 
Anaplasi 
Metaplasi; 
raplasis. } 
Larval 
or 
YOUIILC- 
2 Nepionic. 
r Auanepionic. 
J Metanepionic. 
( Paranepionic. 
Immature 
f Ananeanic. 
^ Metaneanic. 
( Paraneanic. 
or 
o Neanic. 
Adolescent. 
Mature 
or 
Adult. 
4 Ephebic. 
' Anephebic. 
Metephebic. 
. Parephebic. 
Senile 
or 
Old. 
5 Gerontic. 
Anagerontic. 
■ Metagerontic. 
Paragerontic. 
Recent researches have in my opinion clearly demonstrated 
that all the stages of development from 2-4 inclusive like the 
embryonic (1) and the senile (5) will have to l)e subdivided in 
studying many groups. These subdivisions are also relatively 
important and their differences are often well deKned. 
The ovum and the extreme degraded substage of the senile 
period represent the widest departures structurally and physio- 
logically from the adult, one being at the commencement and the 
•These stages were ciiuintratcil ami more or less descrihoil under the names of 
Protembryo, Mesetnbryo, Aleteniliryo, Neocmhryo, Typeiiibryo in my jiaper on 
Values in classification, etc., and to these Jackson added Phylembryo in his I'liylo- 
geny of the Pelecypoda, p. 289. 
