Explanation of Plate 9 



Figs. 1-3 Amphissites rugosus Girty. Dorsum, left valve and posterior end, x30. Kinkaid 



formation, loc. 3 p. 49 



4 Amphissites quadratus Cooper, n. sp. Left valve. Holotype, x30. Kinkaid forma- 

 tion, loc. 3 . . . p. 49 



5-6 Amphissites latinodus Croneis and Bristol. Left valve and dorsum, x40. Menard 

 formation, loc. 28 



7-8 Graphiadactyllis tenuis Cooper, n. sp. Dorsum and left valve. Holotype, x20. 



Fayetteville shale, loc. 33 p. 45 



9-12 Graphiadactyllis arkansana (Girty). 9 interior, showing muscle scar; 10-12 left 

 valve, dorsum, and right valve of genotype, Fayetteville shale, loc. 34; x20. 

 (U. S. G. S. type No. 1893) p. 45 



13-15 Amphissites exiguus Cooper, n. sp. Dorsum, left valve and posterior end. Holotype, 



x40. Kinkaid formation, loc. 3 p. 49 



16-17 Ectode?nites magnireticulatus Cooper, n. sp. Dorsum and left valve. Holotype, x30. 



Paint Creek formation, loc. 2 p. 50 



18 Amphissites golcondensis Croneis and Gale. Left valve, x40. Paint Creek forma- 



tion, loc. 2 



19-21 Amphissites carinatus Cooper, n. sp. Dorsum, left valve and posterior end. Holo- 

 type, x30. Glen Dean formation, loc. 11 p. 48 



22 Ectodemites costelliferus (Croneis and Bristol). Left valve, x30. Vienna forma- 



tion, loc. 10 p. 50 



23 Ectodemites ohlongus (Jones and Kirkby). Left valve, x40. Vienna formation, 



loc. 10 p. 50 



24-25 Ectodemites elongatus Cooper, n. sp. Dorsum and left valve. Holotype, x30. Kin- 

 kaid formation, loc. 6 p. 50 



26-27 Venula striata (Croneis and Funkhouser). Dorsum and left valve, x30. Kinkaid 



formation, loc. 28 p. 44 



28-29 Ectodemites ohesus (Croneis and Gale). Dorsum and right valve, x30. Golconda 



formation, loc. 28 p. 50 



30-31 Ectodemites parvus Cooper, n. sp. Dorsum and left valve. Holotype, x40. Menard 



formation, loc. 7 p. 50 



32-34 Amphissites insignis Croneis and Thurman. Left valve, posterior end and dorsum. 

 x30. Kinkaid formation, loc. 3 



35 Ectodemites cf. monomastadis (Coryell and Sohn). Left valve, x30. Menard for- 

 mation, loc. 30 p. 50 



36-37 Discoidella ampla Cooper, n. sp. Dorsum and right valve. Holotype, x40. Renault 



formation, loc. 9 p. 46 



38-39 Discoidella pendens Croneis and Gutke. Dorsum and right valve, x50. Renault 

 formation, loc. 25 



40-41 Ectodemites planus Cooper, n. sp. Dorsum and left valve. Holotype, x30. Golconda 



formation, loc. 8 p. 50 



42-44 Hollinella radiata (Jones and Kirkby). 42, 43 right valves from Glen Dean forma- 

 tion, loc. 1, and Menard formation, loc. 7 ; 44 spineless left valve from Clore 

 formation, loc. 27 ; x20 p. 46 



45 Hollinella granifera (Ulrich). Left valve, broken on antero-dorsal corner, xl5. 



Renault formation, loc. 12 p. 45 



46-47 Ectodemites primus Cooper, n. sp. Dorsum and left valve. Genotype, x30. Kinkaid 



formation, loc. 5 p. 51 



48-49 Hollinella longispina (Jones and Kirkby). Left valves showing broken spines on 



ventral margin, x20. Renault formation. Iocs. 12, 14 p. 45 



50-51 Ectodemites hicarinatus (Croneis and Thurman). Dorsum and right valve, x30. 



Kinkaid formation, loc. 28 p. 49 



[84] 



