384 TRANSACTIONS OF THE WAGNER FREE 



This fine species is rather abundant in the Shell Creek Pliocene and not 

 uncommon in the Caloosahatchie marl. In some respects it is intermediate 

 between the sections of Turbo now recognized, and between Turbo proper and 

 Astralium. Its nearest relative is a species now living on the western coast 

 of Mexico, but it is also akin to both the Floridian species of Senectns. 



Genus ASTRALIUM Link. 

 Subgenus Lithopoma Gray. 

 Astralium (Lithopoma) chipolanum n. s. 

 Plate 1 8, figure 6 a. 

 Older Miocene of the Chipola group, in the lower bed at Alum Bluff, 

 Chattahoochee River, Florida, Burns. 



Shell small, elevated-trochiform, with flattened sides and base and seven 

 or eight whorls ; nucleus minute, the first two or three whorls flattened above, 

 coiled in a single plane, then taking on the adult habit in the remainder of 

 the shell ; periphery keeled, the carina furnished with ten or twelve triangular, 

 imbricate spinose projections, underneath which the suture is closely ap- 

 pressed ; above, between the suture and the periphery, are five low spiral, 

 beaded bands, between which are single smaller intercalary threads, all of 

 which march straight around the whorl without fluctuation ; on the base be- 

 tween the periphery and pillar are about eight beaded spirals, alternated in 

 strength ; across the spiral sculpture, obliquely, especially toward the apex, 

 run well-marked but not lamellose incremental lines; pillar narrow, arched, 

 with a faint groove behind it, terminating in one or two feeble tubercles ; 

 aperture rounded quadrate, outer lip thin, body with a wash of callus. Alt. 

 1 1.5 ; max. diam. i i.o mm. 



This interesting little shell is without doubt the forerunner of the follow- 

 ing species, but differs from it and from all the recent forms in the low recti- 

 linear sculpture and the absence of any plications on the side of the whorl 

 except at the periphery. The operculum is unknown. 



Astralium (Lithopoma) precursor n. s. 

 Plate 18, figure 8. 



Pliocene marls of the Caloosahatchie and Shell Creek, Florida. 



Shell elevated, subacute, eight-whorled; nucleus small, smooth, of a single 

 whorl ; subsequent whorls sculptured with numerous subequal, flexuous, 

 spiral threads, with narrower interspaces, crossed obliquely by numerous 

 elevated, imbricated incremental lamellae, so close-set that the entire surface 

 when intact is densely scaly with minute flexuous, irregular scales ; at right 

 angles to the incremental lines the surface of the whorl is plicated from the suture 

 forward with low irregular ridges, which frequently fail before reaching the 

 periphery, and vary in number as well as in strength, generally being more 

 numerous than the peripheral nodules ; periphery rounded, pinched up into 



