192 TOBNATELLIDES. 



This species is known only by the above description and a 

 nameless figure, without locality, in Reeve's Iconica, which 

 Pfeiffer referred with doubt to T. achatinoides. The shell may 

 possibly turn out to be a Ferussacia from northern Africa. 



Genus TORNATELLIDES Pilsbry. 



Tornatellides PILS., Nautilus xxiii, March, 1910, p. 123, type 

 T. simplex Pse. 



The shell is small, dextral, ovate-conic or oblong, perforate 

 or umbilicate in all post-embryonic stages; thin. Aperture 

 ovate, armed with a parietal lamella and one or two columellar 

 lamellae (often wanting in the adult stage) ; palatal wall 

 simple. Reproduction viviparous. Mantle maculate with 

 black. 



Type T. simplex Pse. Distribution, Islands of the Pacific. 



Tornatellides closely resembles Tornatellaria. The original 

 definitions of the two groups were not diagnostic for the entire 

 series now known ; but the observation first made by the junior 

 author that the species of Tornatellides are viviparous, while 

 the Tornatellaria are oviparous, like Auriculella, confirmed 

 the distinction, and cause us to rank both groups as genera. 

 This distinction is not so difficult of application as might be 

 supposed, for the dry shells of Tornatellides usually will be 

 found to contain embryo shells when broken open. Even fossil 

 shells often contain them. Moreover, except in the group of 

 T. cyphostyla, the whorls are more convex in Tornatellides, 

 the base is convex or saccate, and the periphery is not angular. 

 One soon learns to distinguish the two genera on sight, with 

 very few exceptions. The generic position of nearly all the 

 species has been verified by finding the embryos. 



Specific characters. The species of this genus show a 

 greater differentiation than those of any of the other genera 

 of the family. The axis of Tornatellides is invariably hollow 

 up to the initial whorl. The perforation is sometimes quite 

 small throughout the immature stages, suddenly widening at 

 the last whorl. In other forms it is widely open from the first, 

 appearing well-like, viewed from below, and not rapidly en- 

 larging in the last whorl. The number of whorls varies from 



