PLATE XII. 



IIeteroceras Conradi, Morton, Sp. (page 100.) 



Figure 1. The best specimen of this species in the collection. 



" 1 a. Detached portion of the uncoiled part of the same specimen. 



" 2. Fragment of another individual, consisting of one of the early whorls, to 

 show the width of the ximbilicus at this stage of growth. 



" 2 a. Another view of the same. 



" 3. Fragment of a nearly adult shell, showing an upward curve of the whorl 

 r>revious to uncoiling. 



