132 



CALIFORNIA ACADEMY OF SCIENCES. [Proc. .^d Ser. 



Table of Ontogf:netic Stages. 



Stages. 

 Embryonic ( i 



Stages. 

 Embryonic 



Larval 



( 2 ) Nepionic 



Substages. 



Phylembryonic 



Ananepionic \ 

 Metanepionic \ 

 Paranepionic ) 



Adolescent { 3 ) Neanic 



Adult ( 4 ) Ephebic 



Senile { 5 ) Gerontic 



/ 



Ananeanic 



Metaneanic 



Paraneanic 



i Anephebic 1 

 -j Metephebic >- 

 ' Parephebic ) 



) 



Anagerontic 



Metagerontic 



Paragerontic 



Comparison with 

 Phytogeny. 



Phylembryonic 

 Phylonepionic 



Phyloneanic 



Phylephebic 



Pliylogerontic 



& 



< 



E 



a, 



With the embryonic stage the paleontologist can do noth- 

 ing except the very last substage or phylembryo, when 

 molluscs, brachiopods, and other groups begin to secrete 

 their shell; but all later stages are easily accessible in well 

 preserved material. 



A classic example of correlation of ontogeny with phylog- 

 eny is the genealogy of the Prolecanitidae, worked out by 

 Karpinsky ^, who has shown that the Carboniferous genus 

 Pronorites goes through the following stages : latisellate 

 protoconch, phylembryonic; with the second suture it 

 becomes an Anarcestes, nepionic; about the end of the 

 first revolution the Ibergiceras stage begins, the end of the 

 larval period ; the second revolution corresponds to Para- 

 ■prolecanites, neanic; on the third whorl begins the Pronoi-- 

 ites stage, adult. Thus with regard to Pronorites the genus 

 Anarcestes is phylonepionic, Ibergiceras is phyloparanepi- 

 onic, Paraprolecanites is phyloneanic. In the same work 

 Karpinsky shows that Medlicottia is a direct descendant of 

 Pronorites., and in its development goes through all the 

 stages of the ancestral genus and adds still others. The 

 first revolution of Medlicottia could not be studied, but the 



' M6m. Acad. Sci. St. P6tersbourg, 7th Ser., Tome XXXVII, No. 2. "Ammoneen der 



Artinsk-?tufe." 



