236 FOOT-NOTES TO EVOLUTION. 
stages with phylogeny is the genealogy of Medlicottia, 
worked out by Karpinsky,* who has shown that the Car- 
boniferous genus Pronorites goes through the following 
stages: latisellate protoconch, phylembryonic; with 
the second suture it reaches the Axarcestes stage, nepi- 
onic; about the end of the first revolution the Jbergice- 
ras stage begins, paranepionic; second revolution shows 
the Paraprolecanttes stage, neanic; on the third whorl 
begins the Pronorites stage, adult.| Thus with regard 
to Pronorites the genus Azarcestes is phylonepionic, 
Lbergiceras is phyloparanepionic, Paraprolecanites is phy- 
loneanic. In the same work Karpinsky has shown that 
Medlicottia is a direct descendant of Pronorites, and in 
its development goes through all the stages of the ances- 
tral genus and adds several more. The first revolution 
of Medlicottia could not be studied, but on the second 
revolution was seen the /bergiceras stage, metanepionic; 
on the third whorl the Paraprolecanites stage, paranepi- 
onic; at the end of the third whorl the Pronorites stage, 
beginning of the neanic; on the fourth whorl the 
Sicanites stage, end of the neanic; on the fifth whorl the 
Promedlicottia stage, anephebic; ‘and lastly, at end of the 
fifth whorl, Med/icottia, adult in characteristics, though 
not yet in size. 
PALEONTOGENY. 
Just as biologists are turning more and more to the 
study of morphology and ontogeny, so the paleontolo- 
gist is striving to find out the life-his- 
tory of fossil species—paleontogeny. It 
will surprise many to.learn that this can 
be done, but in reality the development of many fossil 
General 
statement. 
* Mem. Acad. Imper. Sci. St. Petersburg, vii ser., tome xxxvii, 
No. 2, Ammoneen der Artinsk-Stufe. 
t See Plate IV, Fig. 9. 
