326 TRANSACTIONS OF THE WAGNER FREE 



nineteen strong, transversely-keeled tubercles, separated from the strong 

 similar umbilical rib by an excavated sulcus ; the rib is prominent, and looks, 

 to a casual inspection, as if it were the top of the umbilical wall of the whorl, 

 which is not the case; the shell is depressed, with a wide, thin carina, blunt 

 and slightly undulate on the edge ; both the under and upper surfaces of the 

 whorls are concave ; the keel overhangs the suture in front ; the base outside 

 of the umbilical carina is smooth, with a single fine thread in the bottom of 

 the excavation ; on the summit, above the keel, are four fine beaded or undu- 

 lated spirals, separated by much. wider interspaces, those next the suture 

 stronger than the other two. Alt. 5.5; diam. ii.o mm.; the apical whorls 

 are estimated for, being defective in the type. 



Patulaxis. S. scrobiculatnm Conr. has the shell depressed, feebly stri- 

 ated, with a decumbent peripheral keel ; umbilical carina strongly dentate, 

 with about twenty-five triangular tubercles ; there is a faint, fine transverse 

 fluting or wrinkling on each side of the suture, strongest behind ; the spiral 

 striae are fainter below and not stronger above than the incremental lines ; we 

 have it from the Claibornian, Wood's Bluff and Gregg's Landing, Ala.; New- 

 ton, Miss. ; from Mt. Lebanon, La., and Wheelock, Tex. S. texamim Gabb 

 has the upper surface without spiral striation, the middle of the whorl im- 

 pressed, the suture simple-edged except in the very young, the periphery 

 wider and less decumbent; the umbilicus smaller, with the carina very finely 

 transversely wrinkled, the base smooth or with a few obsolete spiral lines. It 

 comes from Wahtubbee Hills, Wood's Bluff, La., and Texas. In both the 

 preceding the umbilical wall is marked only by lines of growth, and is flat or 

 slightly concave. 



5. cupola Heilprin (Proc. Acad. Nat. Sci. Phila. 1880, p. 375, pi. 20, fig. 14). 

 Shell dome-shaped, variable in height, whorls excavated above, especially 

 toward the apex, the peripheral keel strongly decumbent ; whole surface, in- 

 cluding the umbilical wall, sharply spirally threaded with fine alternate, ele- 

 vated lines, those between the suture and the sulcus in front on the spire 

 stronger; suture simple or microscopically wrinkled; umbilical keel with ex- 

 tremely fine wrinkles at the edge ; umbilical wall slightly convex, umbilicus 

 large ; whorls seven. Alt. 4.75 ; max. diam. 18.0 mm. It is from Bashia Creek 

 and Wood's Bluff, Ala. "Discohelix" Dixoni Vasseur (Cossm., Par. iii., pi. xi. 

 figs. I, 2), probably the young of 5. patulwn Lam., illustrates the form of the 

 young shells of this group before the periphery becomes decumbent. S. patu- 

 lum of course belongs to this section and is nearly related to, though distinct 

 from, Conrad's S. scrobiculatiim. 



Stellaxis. The representative of this group is Solarhnn alveatum Conr. 

 (-1- bilineahivi Lea). Its simple and sturdy sculpture, stellate umbilicus with 

 spirally striate walls, carrying a single more elevated, fine, undulate thread, 

 nearly smooth surface and sharply marginate base cannot be mistaken. The 

 chief variations are due to the presence or absence of the two faintly im- 



