Ilva.t.] 108 
[April S, 
111 the ]i;iran('niiic subst,i<>e Iraiisition to the eiiliehie staox' takes 
Itlacc, and cliaractoristics derived from the adults of the iiiiinediate 
anrestois in the same genetic phyhim, such as the trapezoidal 
whorl just mentioned, are replaced by characteristics ])eculiar to 
the gx'uus or species. While there are marked distinctions 
between this and the ananeanic substage, the differences are much 
less obvious between this and the ephebic stage except in those 
shells ill wliich this period has degenerate characteristics. In these 
latter, marked distinctions are likely to make their appearance 
owing to the disappearance of external ornaments and markings 
which have been present until near the end of the neanic stage. 
The ephebic stage has not been so fully studied among the 
nautiloids or ammonoids and therefore in both of these orders it 
may be considered questionable whether any subdivisions are 
essential. This stage is much prolonged in some forms of 
Ammonitinae especially those with numerous whorls like the 
shells of Caloceras, Vermiceras, and the like, and it is quite 
probable that when its characteristics have received more atten- 
tion subdivisions will be found to be convenient. 
The gerontic stage lias been so often described that it is not 
essential to go over the ground here, and the proi)osed suppression 
of the terms catabatic and nostic, etc., has been discussed above, 
as Avell as the general meaning of the substages. 
Buckiuan and Bather propose to use the prefix "pliyl" for forms 
occurring in the phylum which represent in their adult characters 
stages in the evolution of the phylum corresponding with those 
in the development of the ontogeny, and give an instructive table 
in which Haeckel's phj^siologic terms are placed side by side with 
those projtosed for the morphic phenomena. In following out 
the same ideas the following table has been constructed, which 
differs from theirs in the use of nepionic, as stated above, and 
also in the use of phylanaplasis, phylometaplasis, and i)hylopara- 
plasis as correspondents of the siiuihir ontogenic terms. 
St'MMAKv, taklk rir. 
0)itO(jc)i]i. Plnjloijrnij. 
(Knibryonic. 
Nepionic. riiyl;ui;iplasi 
Neanic. 
Fliylembryonic. \ 
Pliylonepionic. j-Epacme. 
Fhyloneanic. J 
Metaplasis < Epliebic. Pliylometaplasis < Pliylephebic. i Acme. 
Paraplasis < Gerontic;. Tiiyloparaplasis < Pliylogerontic. I Paracme. 
