2o Bulletin 27 140 



5, the 1st small and smooth, the 2nd and 3d with from 3-5 strong 

 spirals ; on the later whorls, the sculpture consists of fine, even, 

 raised spirals, covering the entire upper surface and the peripher- 

 al carina ; suture distinct, bordered posteriorly by the peripheral 

 carina, anteriorly by a narrow, Sat space which is defined b3^ a 

 2nd lower carina ; base flattened, or only slightly convex, cov- 

 ered with fine spirals becoming coarser around the umbilcus ; 

 mouth subovate. 



Greater diameter 10, height 8 mm. 

 This is a local species, known at present only from Suffolk. 

 The carina just above the periphery, the fine, even spirals and 

 the open umbilicus are the distinctive characters. 

 Yorktowyi formation ; Suffolk, Va. 



CcJiiostoma (Eutrocfrus) shackelfordensis, Plate 2, Fig. 3 



Shell of moderate size, depressed, with flat upper whorls, a 

 conic spire and flattened base ; periphery with 2 prominent ca- 

 rinae, grooved between ; umbilicus small ; whorls about 5, the 

 1st probably smooth, the 2nd and 3d with 3, 4 or 5 raised, sub- 

 equal spirals ; on the later whorls, the spirals become low and 

 irregular, and assume the appearance of impressed lines ; on the 

 4th whorl, these spiral lines are crowded close to the surture and 

 to the periphery, and with a smooth area between ; on the last 

 whorl, the whole space is covered with fine, even spirals ; suture 

 deep, excavated, the whorls coiling on the lower carina ; the su- 

 ture is bordered in front by a raised line which is either smooth 

 or beaded ; on the last whorl, this sutural line is made up of 3 

 spirals, similiar to those covering the rest of the surface of the 

 whorls ; base flattened with impressed spirals, small and regular 

 on the area bordering the periphery, few, coarse and groove- 

 like around the umbilicus ; mouth subovate. 



Greater diameter p, height 7 mm. 



This species may be compared with C. cyclus Dall which 

 it resembles in shape and general characters but differs from that 

 species in its manner of coiling. In C. cyclus, the sutures are 



