STEOBILOPS, S. G. DISCOSTROBILOPS. 47 



subspecies, in central European Tertiary. In all of its char- 

 acters the Tertiary species agrees so completely with the living 

 S. Jiuhhardi that the relationsliip appears to be well estab- 

 lished. See PI. 8, figs. 10-13, S. uniplicata (Sclbg.), Hydro- 

 bienschichten, Budenheim bei Mainz ; Lower Miocene. 



The parietal lamella of S. huhhardi generally appear to be 

 smooth, but under a high power the rounded edge is seen in 

 the most perfect specimens to bear irregularly and sparsely- 

 placed little points directed towards the aperture and some 

 minute granulation, but without a trace of nodes. 



15. S. HUBBARDi (A. D. Brown). PI. 7, figs. 1-3 (type). 



The shell is subdiseoidal with very low spire, rounded peri- 

 phery and convex, broadly umbilicate base ; width of umbilicus 

 contained 3% times in that of the base. The whorls are 

 strongly convex, increase slowly, and the last descends a little 

 to the aperture. Surface light brown (opaque in the "dead" 

 type, but when living doubtless glossy and somewhat trans- 

 lucent). Initial 1% whorls pale, minutely granulose, the rest 

 with slightly irregular sculpture of close, retractive riblets, 

 about as wide as their intervals, weaker and partly obsolete on 

 the base, where close, weak, microscopic spiral lines are seen. 

 The aperture is rounded-lunate, the lip well expanded and 

 thickened within. The parietal lamella is somewhat elevated 

 and triangular, reaching the edge of the parietal callus. Infra- 

 parietal lamella very low, inconspicuous, weakly emerging, but 

 not to the edge. Both enter slightly further than one-third 

 of a whorl; between them near their inner ends there is a 

 thread-like interlamellar lamella. At about a third of a whorl 

 within there is a series of four basal folds: the first one sit- 

 uated where the basal curves into the columellar floor; the 

 second, stout and erect, in the middle of the basal wall; the 

 third one small; the fourth near the periphery and longer 

 than the others. 



Height 1.2, diam. 2.6 mm. ; 4i/2 whorls. Type. 



Texas: Indianola, Calhoun Co., in the coastal plain; forms 

 of the species occur also in northeastern Mexico, Jamaica, 

 Cuba, Bimini Islands on the western edge of the Bahamas, 

 Bermuda, Florida, Georgia and Mississippi. 



