144 SYSTEMATIC PALEOXTOLOGT 



Family CASSIDIDAE. 



Genus MORIO Montfort. 

 MOKIO BEEVIDENTATA (x\ldrich). 



Plate XXIV, Fig. 7. 



Cassidaria hrevidentata Aldrich, 1885, Jour. Cin. Soc. Nat. Hist., p. 1.52, pi. iii, fig. 20. 



Description. — "Shell, oblong-oval, whorls seven; suture, channeled; 

 surface covered with fine revolving striae; coarser, distant lines upon the 

 body whorl, giving the shell the carinated aspect of the genus; lines of 

 growth fine, a few coarser ones showing on the line of the tubercles; 

 apex, smooth; whorls of the spire carinate and slightly tubercled; a row 

 of upright longitudinal nodes on the shoulder of the body whorl, none 

 below; a single, strong varix on the body whorl; aperture, ovate; inner 

 lip spreading over the whorl, with three plications on the upper part, 

 smooth in the central part and plicate below; outer lip reflected, plicate 

 on the inner edge above and below, smooth in the center; canal, narrow, 

 strongly twisted." Aldrich, 1885. 



Length, 30 mm.; width, 30 mm. 



ccurre7ice.^ AqviA Formation. 1 mile southeast of Mason Springs, 

 2 miles below Potomac Creek. 



Collection. — Maryland Geological Survey. 



Family CYPRAEIDAE. 



Genus CYPRAEA Linne. 

 Cypeaea smithii Aldrich, 

 Plate XXIV, Pig. 8. 



Cypraea smithii Aldrich, 1886, Geol. Survey, Ala., Bull. 1, p. 33, pi. y, fig. 3. 



Description. — " Shell oblong-ovate, rather flat, surface smooth; labium 

 crenulate within, smooth on the base and flattened, reflected somewhat 

 and raised above base of shell; aperture slightly crenulate within, ex- 

 panded below." Aldrich, 1886. 



Fragments of a Cypraea which in their somewhat imperfect condition 

 show no characters which would prevent their being referred to C. 

 smithii are fairly abundant in the Potapaco member, but seem to be 

 much restricted in vertical range. 



