.M.MIVLANI) OKOr.OfiU'Ar. SIKVIA' 137 



longitudinal costae, wliidi do imt extend idxjve the shoulder; ribs 

 crossed by numerous more or less alternatiii<^ ridfjes, of which two on 

 the body whorl, al)out half-way between the shoulder and the anterior 

 end, are noticeal)ly larj^er Ibaii tlie others; finer lines of growth cross 

 the ridges forming a somewhat lugose sculpture; above the shoulder 

 smooth with a few simill i-evoiving raised lines and still smaller arcu- 

 ated lines of growth. 



The figured specimen is the only one known. It resemliles very 

 closely McIoiKjciKi suhairiiKild of the Paris Basin Eocene. There is also 

 a resendjlance to PoplUiiKi shniiinea rar. Harris' from Claiborne, Ala- 

 bama. 



Length, 3-i mm.: width, 18 mm. 



Occurrence. — Aquia FoRirATiox. Potomac Creek. 



Collection. — P]iiladel[)hia Academy of Natural Sciences (No. 6880 of 

 the Lea Memorial Collection). 



Genus TUDICLA Bolteii. 

 TUDICLA MAEYLAXDICA n. sp. 



Plate XXIII, Figs. 1, la, lb. 



Description. — Spire flat, concealed except on top by the body whorl 

 which is large, much expanded above, but rapidly contracting below; 

 surface marked by lines of growth, and fine, revolving wrinkles which 

 become strong toward the beak; periphery of body whorl with spines of 

 moderate size; beaks long, narrow^, reflexed; columella twisted obtusely. 



This species differs from P. pyrula Aid. in not having the elevated 

 spire shown in Harris' figure of a Midwayan specimen," and also in not 

 having as elevated a spire, as ovate a mouth, nor being as strongly 

 spinose as the Chickasawan specimens. 



Length, 70 mm.; width, 50x35 mm. 



Occurrence. — Aquia Foematiox. 2 miles below Potomac Creek. 



Collection. — Maryland Geological Survey. 



iProc. Acad. Nat. Sci. Phila., vol. xlviii, ISOO, p. 474, pi. xx, fig. 2. 

 -Bull. Amer. Pal., vol. iv, pi. xix, fig. 2. 



