EVOLUTION OF THE NUGLEOLITID TYPE PHYLLODE IN THE CASSIDULOIDA 



JURASSIC 



CRETACEOUS 



TERTIARY QUATERNARY 



BAJOCIAN BATHONIAN CALLOVIAN 



OXFORDIAN 



LUSITANIAN 



KIMMERIDGIAN 

 PORTLANDIAN 



NEOCOMIAN 



APTIAN 



ALBIAN 



I 



D G J 



PHYLLODES WITH DOUBLE PORES- NO BUCCAL PORES 



CENOMANIAN 



linute buccol pores 



P 



TURONIAN 



SENONIAN 



• « 



oo 



no buccal ports 



TRANSITIONAL FORMS 



S U W Y 



PHYLLODES WITH SINGLE PORES- BUCCAL PORES 



Cba«t 2.— Tlie evolution of the nucleolitid type pliyilode in the Cassiduloida. The locahty data and location of the specimen of eacl 

 burgtmdiae (Cotteau) ; E, Bolhryopncusles lamberti Fourtau; F, .V. sculalus Lamarck; G. N. gracilis (Agassiz) ; H, Pseudosorella 

 e.rcenlricus (Piaet and Renevier) ; M, Ochetes morrisii (Forhes) ; N. Pygorhynchus columbianus (Cooke) ; O. CenUUa synmsts Kil 

 T Hardouinia emmonsi (Stephenson); U, Pygidiolampas etirynola Clark; V, Pliohmpas gauthien (Cotteau); VV, Rliyncholampas 



, species are recorded in the systematic portion of the t,.t A Nucleolius '"t''./'^"""") -.B',^ pt;/it''^« '.^r^V.^^^o/so" ; U XgiocL,,,. 

 ■ghdensis (Mansfield) ; X, Cassiduius cariboearm 



Lamarck; Y, EMiiolampas crassa (Bell). 



