Explanation of Plate 13 



Figs. 1-3 Sansahella elongata Cooper, n. sp. Dorsum, left and right valves. Holotype, x30. 



Paint Creek formation, loc. 24 p. 59 



4—8 Sansahella declims Cooper, n. sp. 4—6 dorsum, left valve and posterior end of holo- 

 type ; 7-8 dorsum and left valve of another specimen; x30. Golconda formation, 

 loc. 19 p. 59 



9-10 Cyathus ^vetustus Cooper, n. sp. Dorsum and left valve. Holotype, x30. Paint Creek 



formation, loc. 2 p. 61 



11-12 Sansahella lenticularis Cooper, n. sp. Left valve and dorsum. Holotype, x30. Clore 



formation, loc. 4 p. 60 



13-14 Paraparchites inornatus (McCoy). Dorsum and left valve, x30. Renault formation, 



loc. 25 p. 62 



15-16 Sansahella harrisi Croneis and Funkhouser. Dorsum and right valve, x30. Clore 



formation, loc. 26 p. 60 



17-19 Paraparchites cydopeus Girty. Left valve, dorsum and right valve, xl5. Golconda 



formation, loc. 18 p. 61 



20-21 Paraparchites kinkaidensis Croneis and Thurman. Dorsum and left valve, x20. 

 Kinkaid formation, loc. 5 



22 Microparaparchites inornatus Croneis and Bristol. Left valve, x40. Clore forma- 



tion, loc. 4 



23-25 Microparaparchites erectus Cooper, n. sp. Dorsum, left valve and posterior end. 



Holotype, x40. Golconda formation, loc. 19 p. 61 



26-28 Microparaparchites spinosus Croneis and Gale. Posterior end, dorsum and right 

 valve. Holotype, x30. Glen Dean formation, loc. 23 



29-31 Sansahella tumida Coryell and Sohn. Posterior end, dorsum and left valve, x20. 



Menard formation, loc. 20 p. 61 



32-35 Sansahella ampla Cooper, n. sp. Dorsum, left valve, venter and posterior end. 



Holotype, x20. Paint Creek formation, loc. 2 p. 59 



36-41 Sansahella truncata Cooper, n. sp. 36-38 posterior end, dorsum and right valve of a 

 reversed specimen; 39-41 dorsum, left valve and posterior end of a normal speci- 

 men, holotype; x30. Golconda formation, loc. 22. (Note reversal of another 

 species, figs. 46-51) . p. 60 



42-43 Sansahella parallela Cooper, n. sp. Dorsum and right valve. Holotype, x30. Vienna 



formation, loc. 10 p. 60 



44-45 Sansahella vinitaensis (Harlton). Dorsum and left valve, x30. Renault formation, 



loc. 25 p. 61 



46-51 Sansahella hradfieldi (Coryell and Sohn). 46-48 posterior end, dorsum and right 

 valve of a reversed specimen; 49-51 dorsum, left valve and posterior end of a 

 normal specimen ; x30. Golconda formation. Iocs. 22, 19 p. 59 



52-53 Sansahella ovata Cooper, n. s. Dorsum and left valve. Holotype, x30. Paint Creek 



formation, loc. 24 p. 60 



92 



