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 Anarcestes stage, nepi- 

 onic ; about the end of the first revolution the Ibergice- 

 ras stage begins, paranepionic ; second revolution shows 

 the Paraprolecanites stage, neanic; on the third whorl 

 begins the Pronorites stage, adult. f Thus with regard 

 to Pronorites the genus Anarcestes is phylonepionic, 

 Ibergiceras 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 Ibergiceras 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, Medlicottia, 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 



statement. .,, . , , , • 



will surprise many to learn that this can 



be done, but in reality the development of many fossil 



* Mem. Acad. Imper. Sci. St. Petersburg, vii ser., tome xxxvii, 

 No. 2, Ammoneen der Artinsk-Stufe. 

 \ See Plate IV, Fig. 9. 



