part 4] CAMBRIAN HORIZONS OF COM LEY. 381 



Micromitra sp. indet., X 4, see p. 328 ; horizon Be. 



Fig. 18. Ventral valve, with lateral view [2134]. 

 19. Surface of another specimen [2133] X 8. 



Walcottina elevata, gen. et sp. nov., X 4, see p. 337 ; horizon Ab r 



Fig. 20. Type-specimen, ventral valve ; a, internal cast, lateral view [1914] ; 

 b, exterior, from a squeeze of the external cast ; c, lateral view of 

 same [1916]. 



21. Dorsal valve [1916], with lateral view. 



22. Ventral valve, posterior view of sandy cast [2282]. 



Walcottina lapworihi, gen. et sp. nov., X 4, see p. 336 ; horizon Ab^ 



Fig. 23. Type-specimen, ventral valve, exterior : a, summit view ; b, lateral 

 view; c, posterior view [King 1] 



24. Ventral valve, exfoliated to the inner layer of shell, with lateral view 



[King 1]. 



25. Surface characters, X about 12. 



Micromitra (?) sp. indet., X 4, see p. 334 ; horizon Kb l . 



Fig. 26. Interior, with section in outline [2183]. 



Obolella (?) groomi Matley, X 5, see p. 345 ; horizon Ab r 



Fig. 27. Ventral (?) valve, exterior, with lateral view [2226]. 



Bradoria (?) sp., X 5, see p. 368 ; horizon Ac . 



Fig. 28. Right valve [14536] in the British Museum (Natural History) Col- 

 lection; a, lateral view ; b, terminal view; c, dorsal view. 



Plate XXII. 

 Obolella atlantica Walcott, var. transversa nov., X 5, see p. 344; horizon Ac r 



Fig. 1. Type-specimen, dorsal valve, internal cast [810]. 



2. Ventral valve, internal cast, with lateral outline [807]. 



3. Do. do. do. [2162]. 



4. Dorsal valve, exterior [53]. 



5. Apex of ventral valve, exterior [2189]. 



Obolella atlantica Walcott, var. comleyensis nov., X 5, see p. 342 ; 

 horizons Acj to Ac 3 . 



Fig. 6. Type-specimen, ventral valve, internal cast, with lateral outline 

 [1288], Ac 3 . 



7. Dorsal valve, internal cast with portion of shell adhering [785] ; 



also lateral outline, Ac,,. 



8. Ventral valve, exterior, with lateral view [2159], Ac 2 . 



9. Do. do. internal cast, with lateral outline [766], Ac 2 . 



Lmgulella viridis, sp. nov., X 6, see p. 341 ; horizons Ac^ & Ac 5 . 



Fig. 10. Ventral valve, internal cast, with lateral outline [35]. 



11. Dorsal valve, exterior, with lateral outline [1996]. 



12. Type-specimen, dorsal valve, internal cast, with lateral view [97]. 



Obolus parvulus, sp. nov., X 6, see p. 338 ; horizons Ac, to Ac 5 . 



Fig. 13. Type-specimen, dorsal valve, internal cast, with lateral outline [1512], 

 Ac 2 . 

 14. Dorsal valve, interior much exfoliated, showing a median ridge 

 representing the median depression of the exterior [1512], Ac.,. 



