194 



Williamson — West American Mitridse, 



West Coast Mitras, Nat. Size. 



Figs. 1 and 2. Mitra idx, young. San Pedro, California. 



Figs. 3 and 4. Mitra idse, adult. San Pedro, California. Epidermis partly removed. 

 No. 4 collected by Mrs. E. A. Lawrence 



Fig. 5. Milra idas, adult. San Pedro, California. Epidermis wholly gone, color of shell 



light brown. Collected by Mr. Delos Arnold. 

 Fig. 6. Mitra/ultoni E. A. S. Pt. Abreojos, Lower California. Collected by Mr. Henry 



Hemphill. 



Fig. 7. Mitra orieiUalis. Peru. 



Genus MITRA Lam. 



Mitra — typical — is mitriforni, thick, with spire elevated, sharp apex, 

 aperture narrow with a notch in front; " columella obliquely plicate; lip 

 rather thick, smooth within." The animal is described as having in gen- 

 eral a short foot, siphon somewhat short, proboscis cylindrical, eyes on 

 tapering tentacles, the latter close together on a long and flat head ; color 

 white. The dentition of the group is an important factor. 



