214 SYSTEMATIC PALEONTOLOGY 



SCALA (OpALIa) RETICULATA n. Sp. 



Plate LIII, Fig. 5. 



Description. — Shell small, slender, about ten-whorled ; whorls convex 

 and very closely set; varices very small but numerous, about 35 on the 

 body whorl, and decreasing in number but increasing in size toward the 

 apex; intervarical spaces with six rounded, raised, revolving lines with 

 finer intermediate ones, both sets being absent above the suture for about 

 twice the ordinary interval of the larger ones; mouth round; base flat- 

 tened, covered with obsolete revohing lines. Over the greater part of 

 the surface of the shell the varices and revolving ril:)s are of about equal 

 prominence and at equal distances, thus giving a very noticeable reticulate 

 appearance. 



Length, 9 mm. ; diameter, 3 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collections. — Maryland Geological Survey, Cornell University, U. S. 

 National Museum. 



ScALA (Opalia) prunicola n. sp. 

 Plate LIII, Fig. 6. 



Description. — Shell of medium length and acuteness, with about eight 

 whorls ; whorls strongly and regularly convex, except at the periphery of 

 the body whorl where there is a sharp angle ; revolving ribs obtuse, irregu- 

 lar in distance, six in number; interspaces gently concave, marked with 

 very fine, closely-set, revolving threads ; entire surface of the shell covered 

 with very fine, closely-set„ longitudinal threads which cross the revolving 

 ribs; varices small, irregular; base with fine« radiating, and finer con- 

 centric lines. 



This species has a superficial resemblance to S. reticulata, but differs 

 in lacking distinct and regular varices, in possessing very fine revolving 

 and longitudinal sculpture, and in having more distant and more acute 

 revolving ribs. 



A single specimen has been found. 



Length (of fragment), 10 mm.; diameter, 5.5 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — Maryland Geological Survey. 



