SAGDA. 61 



Animal viviparous, the young at birth being depressed-globose, 

 flattened above, thin, translucent, perforated ; composed of 2 

 whorls; measuring nearly one-fifth the diameter, of the adult. We 

 have observed young shells in specimens of cookiana, foremaniana 

 and ambigua. 



Section Hyalosagda Martens. Shell perforate or umbilicate, 

 glassy, thin and depressed. Aperture with -no internal lamellae or 

 teeth. Type S. similis, pi. 16, figs. 18, 19, 20. 



Animal oviparous, the eggs short-oval, with a hard, white, smooth 

 calcareous shell ; the length of its longest axis contained 5 to 6 times 

 in the diameter of the shell. We have found eggs in S. haldemarti- 

 ana and S. similis. 



Subgenus ODONTOSAGDA Martens. Small, thin and umbilicated ; 

 internal lamina? interrupted ; columella thin. 



The extreme difficulty of the genus, and the inadequacy of the 

 accounts of it in the works of Pfeiffer, Reeve and Tryon, induce me 

 to offer the following key to the species. Shuttle worth has published 

 an excellent revision of the group. All known Jamaica species are 

 represented in the collection of the Academy. 



Key to the species of Sag da. 



I. Aperture provided with internal teeth or lamina?. 



a. Basal lamina either interrupted, or less than J whorl in 

 length ; base very convex ; form subglobose or globose-conic. 

 b. Base deeply impressed at columella ; basal lamina 

 interrupted. 



c. Globose-conic ; solid, strong, yellow ; col- 



umellar fold weak or obsolete; basal lamina 



interrupted forming several teeth ; whorls 9 ; 



alt. 21, diam. 22 mill. cookiana. 



bb. Base not deeply impressed ; basal lamina continuous ; 



columella with a nodule-like fold. 



c. Globose-pyramidal; base globosely convex, 

 not impressed at columella ; solid, strong, 

 yellow ; columellar fold a strong nodule, 

 not entering ; basal lamina very strong, i 



