VARICELLA. 49 



II. Sculpture of subequal striae or riblets, with the usual 

 varices. 



a. Spiral lines or grooves well developed on the later 

 whorls; varices and outer lip nearly straight, not 

 arched forward or angular; rather large shells of 

 Haiti. 



b. Later whorls evenly rib-striate, with impressed 



spiral lines; spire rather short; embryonic shell 



of 3!/3 Whorls, closely striate except the first % 



whorls. Section Varicellidea. 



& 1 . Later whorls with close, irregular folds and 



spiral sulei, irregularly pitted; spire long; apex 



unknown. Section Varicellopsis. 



a 1 . Not perceptibly striate spirally. 



1). First % to li/o of the embryonic whorls smooth, 

 the rest striate or ribbed, Jamaican forms, 

 c. Columella straightened, very weakly, ob- 

 liquely truncate ; shell slender. 



Section Varicellula. 



c 1 . Columella strongly twisted, conspicuously 

 truncate ; shell of moderate or rather large 

 size, sculptured with riblets or rib-striae, 

 the intervals as wide as the riblets ; outer 

 lip arcuate or angular. 



Section Varicellaria. 



c 2 . Columella strongly twisted and truncate; 

 21/2 embryonic whorls, the first l 1 /^ smooth, 

 the next with widely spaced grooves ; adult 

 sculpture of sinuous rib-strias wider than 

 the intervening grooves; outer lip arcuate. 

 No colored varix-streaks. 



Section Varicellina. 

 6 1 . First 2% to 3 whorls smooth. 



c. Later whorls with sculpture of even stride 



between the varices, the stride wider than 



their interstices, or with irregularly spaced 



grooves. Section Varicella. 



c 1 . Later whorls without grooves or stria be- 



