PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 28a 



"Chiton" Gray anus Kouinck, 1857. Upper Siluriau. 



" ChUon" Wrightiantis Koninck, ditto. 



^' ChitoneUus" Hancoddanus Kirkby, Proc. Geol. Soc, 18.'>9, pi. 10, figs. 1-13. Penuian, 

 England. 



'^Chiton" cordaius Kirkby, ditto, figs. 24-29. 



"Chitonellus" distordis Kirkby, ditto, tigs. 28-:«0. 



" Chitonellus" aniiquiis Howse, Kirkby 1. c, figs. 14-23. Permian. 



"Chiton" cordifer Koninck, Descr. An. Foss. Terr. Carb. Belg., 1844, p. 324, pi. 22, fig. 

 5 a, h (teste Eyckliolt). Carbouiterous of Belgium. 



*' Chiton" corntgatiis Saudberger (pars), p. 238, pi. 26, figs. 22, 22 ft, 22 f, 22(7, 1856. 

 Devonian and Lower Devonian of Vihnar and Ehrenbreitstein. 



"Chiton" sagittalis Sandberger, I.e., p. 239, pi. 26, figs. 23 a, b. Same locality? 



Suleochiton Grayi RyckhQlt, Journal de Coneliyl., 1862, p. 2."i9, pi. xii, f. 14. Carbonif- 

 erous of Vis6, Belgium. 



ABSTRACT OF ALL THE GENERA. 



Order POLYPLACIPHOEA. 



Section I. — Cliitone.s regulares. 



Head aud tail plates .similarly articulated. 



A. Leptoidea. 

 lusertioii i>lates obsolete or, if present, nnslit. 



(Extinct forms.) 



1. Hehninfhochiton Salter. 



2. Gri/phochiton Gray. 



a. Chonecliiton Cpr. 



3. Priscoehiton Billings. 



7. Leptochiton Gray. 



a. Deshayesiella Cpr. 



8, Hanleyia Gray. 



4. Pferochiton Cpr. 



a. f Loricites Cpr. 



5. ProboJaum Cpr. 



6. Cymaiochifon Dall. 



(Eecent foDiiH.) 



9. HemiHrihrnm Cpr. 

 10. Mieroplax Adams and Angas. 



B. Ischnoidea. 



Insertion x)lates sharp, smooth, fissured ; with eaves. 



*]Sro pores on girdle. 



11. Tracliydermon Cpr. 



a. Trachyradsia Cpr. 



12. Callocluton Gray. 



a. Stereocliiton Cpr. 



13. Tonicella Cpr. 



14. Schizoplax Dall. 



15. Leploplax Cpr. 



16. Chwtopleura Shuttle worth. 



a. Ma,ugerella Cpr. 



17. Sponyiochiion Cpr. 



20. Callistoplax Cpr. 



21. Angasia Cpr. 



22. Newcombia Cpr. 



18. Ischnochiton Gray. 



a. Stcnoplax Cpr. 

 h. Stenoradsia C\n: 

 <: I><chnopJax Cpr. 



d. Heterozona Cpr. 



e. Ischnochiton s. s. Cpr. 



/. Ischnoradf:ia Shnttleworth. 

 g. Lepidoph'urns Cpr. 

 7). Lcpidoradfiia Cpr. 



19. Callislochiton Cpr. 



**With girdlepores. 



23. Ceratozona Dall. 



24. Pallochiton Dall. 



