VI 



YORKSHIRE TYPE AMMONITES 



Dec. 



and papers are readily identifiable from works on Ammonites and 

 from books of reference. 



In citations a comma between the trivial name and the author 

 indicates the author as the giver of the name at the time ; but a semi- 

 colon, that the author is quoting his own or another writer's previously 

 given trivial name. Thus, A. bisulcatus, Bruguiere, and A. bisculatiis ; 

 d'Orbigny ; A. petlos, Quenstedt, 1849 ; but A. pettos ; Quenstedt, 1883. 



Terminology 



Technical terms are necessary, but difficult to remember. Therefore 

 a few that are important will be chronicled below, with explanations 

 purposely as abbreviated as possible.^ Necessary new terms are marked 

 by broad face type. 



Biological Terms 



Growth Stages : — 



Embryonic 



Nepionic 



Neanic 



Ephebic 



Gerontic 



larval, or young. 



adolescent. 



adult. 



senile. 



These terms refer to the individual development, ontogeny ; by 

 the addition of phylo- they denote racial development, phylogeny. 



Structural Stages : — 



The building up takes place during the first three growth stages, 

 the completion is accomplished in the ephebic, and the decline happens 

 in the gerontic stage. 



Or, 



Anagenesis 

 Catagenesis 



Anagenesis 

 Catagenesis 



elaboration 

 simpHfication 



of 

 characters. 



aggradational \ development of 

 degradational J characters. 



Biogenetic Terms 

 Tachygenesis 



Earlier inheritance of characters : 

 hence the characters of adult A will 

 be those of adolescent B, its descen- 

 dant, and so on : — hence, adult A 

 is the morphic prefiguration of 

 adolescent B, and the latter the m. 

 representation of adult A. 



I For further terms, definitions, and literature, see Hyatt, Phyl. Acq. Char.; 

 Proc. Am. Phil. Soc. xxxii, 1894, 349; Idv Ceph. in Eastman trans. Z'ittel, Text-book 

 Pal. I, 1900, 502; KucKMAN, Mon. Amm. 1898, Sup. p. i. 



