STROBILOPS. 57 



4. Spire rather highly conic, of 5i/^ to 6 closely coiled whorls ; 



parietal lamellae with nodes. 



Section Coelostrohilops, species 7, 22. 

 Spire low conic, of 4^/^ whorls; lamellae of parietal wall 

 without nodes; no columellar or interparietal lamella. 



Section Nesostrohilops, species 10. 



5. Upper surface finely striate; no interparietal lamella. 



Section Eostrobilops, species 11-14. 

 Upper surface costulate (except in >S^. morsel, which is 

 nearly smooth) ; an interparietal lamella present. 



Section Strobilops proper, species, 1-9, 20, 21. 

 The following grouping will replace that given at the top 

 of page 18. 



r Section Strobilops s. s. 

 /- Q Q+ v,"i J S^^^^^^ Coelostrobilops. 



„ , „ I rs* -r^- 1 -1 * 1 Section Nesostrohilops. 



Strobilops ^ S.-g. Discostrobilops. 1 g^^^.^^ Eostrobilops. 

 y S.-g. Enteroplax. ^ 



Species of Mexico, Central America and West Indies. 

 The following key is to be substituted for that on page 32. 



1. Form approaching discoidal, the height about half the 



diameter ; umbilicus contained 3 to 4 times in diameter. 



8. hubbardi. No. 15. 

 Higher, the spire conic or conoidal (2) 



2. Umbilicus large, nearly one-third the diameter (3) 

 Umbilicus decidedly smaller (4) 



3. Periphery strongly angular. Guatemala. S. salvini. No. 7. 

 Periphery rounded. Grand Cayman I. S. wenziana. No. 22. 



4. Umbilicus small, contained 10-12 times in the diameter (5) 

 Umbilicus contained about 5-6 times in the diameter; 3 or 



4 basal folds (6) 



5. Shell low conic S. strebeli. No. 5. 

 Spire elevated, the height 80 to 90 percent of the diameter 



8. veracruzensis. No. 6. 



6. Outer basal fold weakly developed (or sometimes want- 



ing?) ; Socorro Island 8. hannai. No. 21. 



Outer basal fold well developed (7) 



it I B R A F 



