700 PROCEEDINGS OF THE NA TIONAL MUSEUM. vol. xxxiii. 



125719, U.S.N.M.), were collected by Dr. T. Wayland Vaughan, at 

 Burkes Place, Louisiana. The type shows three and one-half whorls 

 in the umbilicus and measures : Greater diameter, 0.7 mm. ; least diam- 

 eter, 5.1 mm. : altitude, 3.3 mm. 



EXPLANATION OF PLATE LVII. 



Figs. 1-() are enlarged four diameters; figs. 7-9 are natural size. 

 Fig. 1. Planorbis eucosniius, top view. Type. Page 099. 



2. rianorbis eucosmius, bottom view. Type. 



3. Planorbis eueo.smius, profile. Type. 



4. Planorbis eucosmius vaughani, top view. Type. Page 699. 



5. Planorbis eucosmius vaughani . bottom view. Type. 



6. Planorbis eucosmius vaughani, profile. Type. 



7. Planorbis magnificus, profile. Page 698. 



8. Planorbis magnificus, bottom view. 



9. Planorbis magnificus, top view. 



