MAEYLAND GEOLOGICAL SUKVEY 133 



sculptiTred by numerous, approximate, impressed, revolving lines, and 

 variable longitudinal ribs, which stop at the shoulder, leaving a subsu- 

 tural constriction above it. 



The best specimens of this species are in the Philadelphia Academy 

 and are from Potomac Creek. 



The type in the IT. S. National Museum is now labelled '' ' Near 

 Mouth of Potomac Cr.,' G. D. Harris" but it was supposed when des- 

 cribed to have come from Pomonkey Neck. 



Length, 25 mm.; width, 9 mm. The largest specimen has width of 

 12 mm. 



Occurrence. — Aquia Fokmation. Pomonkey Neck, 2 miles below Po- 

 tomac Creek, Potomac Creek, 1 mile northeast of Piscataway. 



Collections. — Maryland Geological Survey, U. S. National Museum, 

 Philadelphia Academy of Natural Sciences. 



MiTEA POTOMACENSIS U. sp. 



Plate XXI, Fig. 11. 



Description. — Shell small; whorls but slightly convex, and not con- 

 stricted below the suture; revolving lines fine, distinct; ribs reaching 

 from suture to suture, and often extending in one continuous line from 

 whorl to whorl; ribs usually sharp and narrow. 



Length, 12 mm.; width, 3.5 mm. 



Occurrence. — Nanjemoy Foemation. Woodstock, Popes Creek. 

 Aquia Foemation. 1 mile northeast of Piscataway. 



Collection. — Maryland Geological Survey. 



Family FUSIDAE. 



Genus LATIRUS Montfort. 



Latieus maeylandicus n. sp. 



Plate XXI, Figs. 12, 12a. 



Description. — Shell subfusiform, five or more Avhorled; body whorl 

 with fifteen, blunt, irregular, longitudinal folds, and a number of re- 

 volving ridges, very prominent on the shoulder and gradually dying out 

 toward the beak; entire shell covered by fine, closely-set, raised, revolv- 



