EXPLANATION OF PLATE XL. 

 Unless otherwise stated, the figures are copied from Ulrich. 



Figs. 1, 2. Ctenobolbina ciliata (Emmons). 



1. Side view of left valve, X 15. 



2. Interior of right valve. 



3-5. Ctenobolbina emaciata (Ulrich). 



3. Left valve, X 20. 



4, 5. Ventral and end views of same. 

 6-8. CtenobolMna alata Ulrich. 



6. Left valve, X 18. 



7. Dorsal edge view of complete carapace, X 25. 



8. Ventral edge view of same specimen. 



9. CtenobolMna bispinosa Ulrich. 

 Right valve, X 18. 



10. CtenobolMna obliqua Ulrich. 



A right valve. X 20, in which some of the flange is missing. 



11. Ctenobolbina oblonga (Steusloff). 



View of a right valve of this species. X 20. (Copied from Steusloff.) 



12. Ctcnobolbina granosa Ulrich. 

 View of a perfect left valve, X 20. 



13, 14. Ctenobolbina fulcrata Ulrich. 



Lateral and posterior views of a left valve, illustrating the usual 

 characters of the species, X 20. 

 15, 16. Ctenobolbina crassa Ulrich. 



Lateral and posterior views of a left valve, X 20. 

 17,18. Ctenobolbina subcrassa Ulrich. 



Lateral views of a left and right valve, respectively, X 20. 

 19, 20. Ctenobolbina punctata Ulrich. 



Lateral and dorsal views of a right valve. X 20. 

 21, 22. Ctcnobolbina papulosa Ulrich. 



Lateral and ventral views of a left valve, X 20. 



23. Ctcnobolbina minima Ulrich. 

 A right valve, X 30. 



24. Ctcnobolbina imprexsa (Steusloff). 



Lateral view of a right valve, X 20. (After Steusloff.) 

 25-27. Ctenobolbina auricularis (Jones). 



25. Lateral right side view of the complete carapace which is slightly 



tilted, X 25. 

 26,27. Ventral and posterior views of the same carapace. (Copied from 

 Jones. ) 



28. Ctenobolbina umbonata (Steusloff). 



Left valve. X 20. (Copied from Steusloff.) 



29. Ctcnobolbina major (Krause). 



Lateral view of right valve, X 15. (After Krause.) 

 30-31. Ctenobolbina loculata Ulrich. 



30. Exterior of an apparently perfect right valve. X 20. 



31. Interior of a left valve, X 20. 

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