6 PROCEEDINGS OF THE XATIOXAL MUSEUM vol.76 



PrATE 3 



Mitrospira longwelli, new genus and species 



Figures 1, 2, 3. Various views of the aperture. Figure 1, looking directly into 

 the aperture. Figure 2, lateral view showing the sinuous outline 

 of the outer margin of the aperture and the pronounced retral 

 swing to the notch keel. Figure 3, the aperture as viewed from the 

 upi)er (umbilicated) side. 



4. View of specimen with the earlier whorls fairly well preserved, 



showing the apex of the spire and the ornamentation. The outer 

 whorl of the specimen has been blocked out, giving the outer 

 whorl as shown not its true width but the width visible when over- 

 lapped by the later whorl. 



5. Lateral view of badly exfoliated specimen, doubtfully referred to this 



species. The specimen shows the most extreme relative height of 

 spire seen. 



U. S. GOVERNMENT PRINTINS OFFICE: I9Z» 



