PLATE LVII. 
PAGE 
Fig. 1. TuRRiTELLA VARIABILIS Conrad 236 
1. Specimen from St. Mary's River. 
Fig. 2. TURRITELLA VARIABILIS var. ALTicosTATA Conrad 237 
2. Specimen from Dover Bridge. 
Figs. 3, 4. TuRRiTELLA VARIABILIS var. cuMBERLANDiA Conrad 237 
3. Specimen from Plum Point. 
4. Another specimen from tlie same locality. 
Fig. 5. TURRITELLA VARIABILIS var. EXALTATA Conrad 238 
5. Specimen from Plum Point. 
Figs. 6-8. TuRRiTELLA VARIABILIS var 239 
6. Specimen of var. B. Plum Point. 
7. Another specimen of the same. Same locality. 
8. Specimen of var. C. Plum Point. 
Fig. 9. Tachtrhtnchus perlaqueatus (Conrad) 239 
9. Ventral view of type specimen. " Calvert Cliffs." Acad. Nat. Sci., 
Phila. 
