Explanation of Plate 10 



Figs, 1-3 Ectodemites tumidus Cooper, n. sp. Dorsum, right valve and posterior end. Holo- 



type. x40. Kinkald formation, loc. 3 p. 51 



4 Polytylites di'versus Cooper, n. sp. Left valve. Holotype, x50. Vienna forma- 

 tion, loc. 10 p. 52 



5-7 Kirkhya hifrons Cronels and Thurman. Dorsum, right valve and venter, x30. Kin- 

 kaid formation, loc. 3 



8-9 Kirkhyella truncata Cooper, n. sp. Dorsum and left valve. Holotype, x40. Menard 



formation, loc. 30 ... , p. 47 



10 Polytylites reticulatus Cooper, n. sp. Right valve. Holotype, x20. Clore formation, 



loc. 4 p. 53 



11-12 Ectodemites quadratus Cooper, n. sp. Dorsum and left valve. Holotype, x30. Paint 



Creek formation, loc. 21 p. 51 



13-14 Kirkhyella sulcata Cooper, n. sp. Dorsum and left valve. Holotype, x50. Paint 



Creek formation, loc. 2 p. 47 



15-17 Polytylites crassus Cooper, n. sp. Dorsum, left valve and posterior end. Holotype, 



x50. Kinkaid formation, loc. 3 p. 52 



18-19 Kirkhyella quadrata Conels and Gutke. Dorsum and right valve, x40. Renault for- 

 mation, loc. 25 



20-21 Kirkhyella gutkei Cronels and Bristol. Dorsum and right valve, x40. Menard 

 formation, loc. 7 



22 Ectodemites warei (Morey). Left valve, x40. Clore formation, loc. 26 p. 51 



23 Polytylites hiforatus (Cronels and Thurman). Left valve, x30. Golconda forma- 



tion, loc. 8 p. 52 



24-26 Polytylites hradfieldi (Cronels and Funkhouser). Dorsum, right valve and posterior 



end, x30. Clore formation, loc. 4 p. 52 



27-28 Kirkhya cf. reflexa Girty. Dorsum and left valve, x20. Golconda formation, loc. 17 p. 47 



29-30 Kirkhya aequalis Croneis and Funkhouser. Dorsum and right valve, x40. Menard 

 formation, loc. 28 



31-33 Kirkhya symmetrica Croneis and Thurman. Dorsum, left valve and venter, x30. 

 Kinkaid formation, loc. 3 



34-37 Polytylites geniculatus Cooper, n. sp. 34-36 dorsum, left valve and posterior end 

 of genotype, Vienna formation, loc. 10 ; 37 right valve, Renault formation, loc. 9 ; 

 x30 , p. 52 



38-41 Polytylites nodohliquus (Croneis and Gale). 38-40 dorsum, right valve and pos- 

 terior end, Renault formation, loc. 12; 41 right valve, Golconda formation, 

 loc. 8; x20 p. 53 



42 Kirkhya fossula Cronels and Bristol. Left valve, x40. Menard formation, loc. 7 



43 Polytylites directus Cooper, n. sp. Right (?) valve. Holotype, x40. Glen Dean 



formation, loc. 1 p. 52 



44 Polytylites elongatus (Cronels and Bristol). Left valve, x30. Kinkaid formation, 



loc. 5 p. 52 



45 Polytylites quincollinus (Harlton). Right valve, x30. Renault formation, loc. 9 • . p. 53 



46 Polytylites ambitus Cooper, n. sp. Left valve, Holotype, x30. Renault formation, 



loc. 12 p. 51 



47-49 Kirkhya humerosa Cooper, n. sp. Dorsum, left valve and venter. Holotype, x20. 



Kinkaid formation, loc. 3 p. 46 



50 Kirkhya elongata Cooper, n. sp. Right valve. Holotype, x30. Paint Creek forma- 

 tion, loc. 2 p. 46 



51-52 Polytylites fossilis (Croneis and Thurman). 51 left valve, Golconda formation, 



loc. 8 ; 52 right valve, Paint Creek formation, loc. 2 ; x30 p. 52 



[87] 



