MARYLAND GEOLOGICAL SURVEY 135 



Length, 4.7 mm. ; diameter, 1.8 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver, Cove Point, 

 Langley's Bluff. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum. 



VOLVULA IOTA VAR. CALVERTA n. Var. 



Plate XXXIX, Fig. 8. 



This form also is cylindrical but differs from var. diminuta in being of 

 much greater proportional diameter. 



Length, 3.5 mm.; diameter, 1.5 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum. 



Volvula iota var, patuxentia n. var. 

 Plate XXXIX, Fig. 9. 



This form is somewhat shorter proportionally than diminuta and also 

 differs from it in being much wider below than above. The sides are 

 nowhere flat in profile but are gently rounded throughout. 



In the National Museum are specimens from Duplin Co., N. C, which 

 are identical with this variety, and which are labeled V. oxytata Bush. 



1 have not seen authentic specimens of that species, but from the figures 

 this would not seem to he the typical form. 



Length, 5.5 mm. ; diameter, 2 mm. 



Occurrence. — Choptank Formation. Jones Wharf, Governor Eun, 



2 miles south of Governor Run. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Cornell University. 



Genus RETUSA Brown. 



Subgenus CYLICHNINA Monterosato. 



Eetusa (Cylichnina) marylandica n. sp. 



Plate XXXIX, Fig. 10. 



Description. — Shell small, nearly cylindrical, slightly smaller at the 

 apex and with a suggestion of a constriction in the middle; surface 



