20-2 



SYNOPSIS OF SPECIES. 



I. Base rounded. 



1, Apertui'e notched or extending into a short canal behind. 



Shell cylindroid ; teeth small, numerous. 1. C. paraUela. 



Shell oval-oblong ; teeth large. 



Back elevated ; spire concealed. 2. C. scalena. 



Back depressed ; spire prominent. 3. C. suhsidua. 



Shell elongate-oval ; surface contused. 4. C. amjnillacea. 

 Shell oval-subpyriform. 



Spire slightly exsert ; tumid ; posterior canal distinct. 



5. C. Archer i. 



Spire nearly concealed ; less tumid ; posterior canal very 

 short. 6. C. Jonesiana. 



Shell globose ; spire exsert ; surface contused. 



7. C. contusa. 



2. Aperture roundly produced behind on left side, not distinctly 



notched posteriorly. 

 Shell cylindroid, spire exsert. 8. C. suhpyrulata. 



Shell cylindroid-subpyriform ; spire umbilicated. 



9. C. hracliypyga. 

 Shell oval-subpyriform. 



Spire concealed, umbilicated ; outer lip much arched 

 behind. 10. C. pyridata. 



Shell pyriform. 



Spire concealed, slightly impressed ; shell under one 



inch long. 11. C. Jfurraviana. 



Spire exposed, deeply umbilicated ; shell two inches or 



so long. 12. C. leptorhyncha. 



Shell globose ; spire convex. 13. C. ovuJatpIla. 



II. Base flat, not winged. 

 1. Inner lip strongly dentate-sulcate. 



Anterior canal much produced, attenuated. 

 Beak straight or nearly so. 



Shell oval-pyriform ; beak with two dorsal tubercles. 



14. C. eximia. 



Shell globose-pyriform ; beak with or without basal 

 tubercles. 15. C. sphcerodoma. 



Beak much upturned, without basal tubercles. 

 Shell oval-oblong, very gibbous. 



16. C. toxorhyncha. 

 Anterior canal short, obtuse, without basal tubercles. 



Shell oblong-subpyriform ; posterior canal subtruncate 

 with a very wide base. 17. C. p)latypyga. 



Shell more oval ; posterior canal narrow, short. 



18. C consohrina. 



