MIOCENE MOLLUSC A AND CEUSTACEA. Ill 



Genus STEOMBINA Morch. 

 Strombina (Amycla) l^vis, n. sp. 

 Plate xx, Figs. 1-4. 



Shell rather less than a medium size for the genus, consisting of eight 

 volutions; spire elevated, apical angle about 30 degrees; volutions slightly 

 convex between sutures and smooth, except for the fine lines of growth, 

 the last one subangular at the middle and constricted below, to form the 

 short beak; aperture narrow, a little oblique, rather more than half as long 

 as the entire body whorl as seen on the front; outer lip thickened exter- 

 nally, forming a distinct, prominent ridge on the outside, inside slightly 

 thickened, denticulate, having six or eight internal ridges; inner lip slightly 

 callous at the upper angle of the aperture; lower channel or canal distinct, 

 deep, slightly reflected on the outer basal rim; beak strong, and marked 

 externally by from twelve to fifteen close, rounded, spiral ridges. Under 

 a magnifier the surface of the volutions show irregular contorted spiral 

 lines which are neither quite parallel to the sutures nor to each other, but 

 which appear like fine threads placed somewhat irregularly, and broken, 

 beneath the enamel of the surface. 



This species does not quite meet the requirements of the genus Strom- 

 bina, but still is more distant from those" of Amycla, while presenting the 

 prevailing features of both genera. The only entire individual seen, the 

 one figured, barely exceeds half an inch in total length, and shows a mam- 

 illar apex; and is a very neat and beautiful shell; but so far as I can learn 

 it has never before been noticed. Another imperfect individual has been 

 about five-eighths of an inch long. 



Formation and locality: In the gray micaceous Miocene marls at Jeri- 

 cho, and a single one from Shiloh, N. J. From the collections of the 

 National Museum, and a single individual has also been recognized among 

 collections from South Carolina in the American Museum of Natural His- 

 tory. 



