Klem — Revision of the Palaeozoic Palae'echinoidea. 11 



Order C. PERISCHOECHINOIDA. 



Fam. I. Lepidocentridae. 



Genus a. Lepidocentrus. 



b. Perischodomus. 



c. Lepidechinus. 

 Fam. II. Lepidesthidae. 



Genus a. Pholidocidaris. 

 b. Lepidesthes. 

 Fam. III. Melonitidae. 



Genus a. Rhoechinus. 



b. Palaechinus. 



c. Oligoporus. 



d. Melonites. 

 Fam. IV. Archaeocidaridae. 



Genus a. Archaeocidaris. 



b. Eocidaris. 



c. Lepidocidaris. 



DOUBTFUL GENERA. 



1. Discocystis. 



2. Echinodiscus. 



3. Eotiaris. 



4. Koninckocidaris. 



5. Leptechinus. 



6. Mvriastiches. 



7. Permocidaris. 



8. Proterocidaris. 



9. Protocidaris. 



10. Protoechinus. 



11. Spatangopsis. 



12. Xenocidaris. 



Palaeectaiiioidea Zittel 1879.* 



Body composed of more than twenty columns of plates, 

 except one order, Bothriocidaroida, which has less than 

 twenty columns. Plates imbricating or not imbricating. 



* Handbuch der Palaeontologie Bd. 1, p. 478. 



