146 Trans, Acad. ScL of St. Louis. 



in Protosurcula^ but the peculiar narrow elevated embryo, per- 

 fectly smooth throughout and without riblets, higher shoulder 

 angle and oblique fasciolar surface, less developed subsutural 

 collar and some other differential characters, will readily serve 

 to separate the two genera, which are perhaps the most charac- 

 teristic and abundant forms of the Lower Claiborne Eocene, — 

 and impart a marked difference in habitus. The species are 

 more numerous than those of the preceding genus, those 

 known to me being outlined as follows : — 



Peripheral carina crenulate, at least on the small upper body whorls, situated 



at the middle and subduplex 2 



Peripheral carina devoid of any trace of crenulation at any point 6 



2 — Larger species, the peripheral carina at or above the middle of the whorls, 



crenulate on the small or nepionic whorls only 8 



Small species, the periphery more obtusely augulate, more feebly carinate 

 and distinctly below the middle of the whorls ; all the whorls apparently 

 crenulate on the periphery ^ 4 



3 — Peripheral carina at the middle of the whorls, apparently duplex, coarse 



but only moderately elavated; between it and the base there is another 

 similar double carina; slightly above it, at the lower part of the oblique 

 fasciolar surface, there is a fine spiral carina; declivous space thence 

 to the fine subsutural collar with two or three very fine spiral threads . 



Texas, Caldwell Co moorei Gabb 



Peripheral carina well above the middle of the whorls ; between it and 

 the base there are two carinae, which are apparently smaller than 

 the peripheral and less elevated. Lignitic Eocene of Wood's Bluff, 

 Ala taomeyi Aid. 



4 — Moderately stout, the subsutural collar small; surface thence regularly 



ascending to the crenulate periphery and having two or three 

 coarse but feeble spiral lines ; surface below the periphery on the spire 

 whorls with two rather coarse and widely spaced carinules in low relief ; 

 below these on the body whorl the surface is closely, evenly lyrate. 

 Upper Claiborne ferruginous sand \_Coiiu8'] pnlcherrima Hellp. 



6 — Peripheral carina double, its upper carinule smaller and less prominent 

 than the lower, the latter a little below the middle ; subsutural carina 

 unusually strong, at some distance below the suture, the surface 

 thence to the upper peripheral carina regularly oblique, with a single 

 carinule at lower two-fifths ; on the larger whorls a few other very 

 minute and inconspicuous threads can be observed ; surface below the 

 lower peripheral carina, with two carinae, the uppermost interval thus 

 formed much the larger, both with an intermediate central and feeble 

 thread ; lyrae on the body whorl moderately coarse, well separated and 

 only occasionally with intermediate threads. Length of a specimen of 6 

 body whorls, 22 mm. ; width, 6 mm. Lower Claiborne Eocene of Lisbon, 

 Ala concinna n. sp. 



Peripheral carina single, narrow but strongly elevated, at the middle; sub- 

 sutural carina, fine ; surface thence to the periphery regularly oblique 



