LEPTINARIA. 287 



Key to Subgenera and Sections. 

 I. Embryonic whorls smooth. 



a. Shell ovate, the 5 to 8 whorls rapidly increasing; 

 parietal lamella present or wanting; viviparous. 



Subgenus LEPTINARIA s. str., nos. 1 to 41. 



b. Shell imperf orate, turrite or ovate, of 6 to 10 slowly 

 increasing whorls; no trace of a parietal lamella; 

 oviparous. Sect. Lamellaxis. 



c. Shell turrite, of 8 to 10 whorls ; parietal lamella long. 



Sect. Neosubulina, no. 42, 43. 



d. Shell pillar-shaped, with large apex and 11 slowly 

 widening whorls; aperture triplicate. 



Subgenus ISCHNOCION, no. 44. 

 II. Embryonic whorls vertically striate. 



Subgenus PELATRINIA, no. 45. 



Subgenus LEPTINARIA. 



The distinction between typical f^eptinaria and the section 

 Lamellaxis cannot be made in all cases, with our present 

 knowledge. The latter group is therefore included here. 



Species of the Antilles and Trinidad. 



L. lamellata is the most widely distributed form of this area, 

 and will probably be found on nearly all the islands, though 

 it has not yet been reported from Cuba or Haiti. It has an 

 extensive distribution in South America. 



1. Parietal lamella present. Lamellata, no. 1. 



2. No parietal lamella. 



a. Shell ovate, the diam. about half the length ; whorls 

 51/2 to 61/2. Monodon, no. 2 ; pallida, no. 3. 



aa. Shell oblong-conic or turrite, the diam. contained 

 21/2 to 3 times in the length ; whorls 6% to 7. 



b. Narrowly turrite; aperture one-third the 

 length. Abdita, no. 5a. 



bb. Oblong- turrite, aperture larger. 



Salleana, no. 7 ; paludinoides, no. 4. 

 aaa. Shell turrite, imperf orate, Subulina-like ; diam. less 

 than one-third the length; whorls 8 to 10. 



