Bulletin 24 48 



interior of umbilicus smooth with a single revolving line and 

 crossed by transverse ribs. 



Height of type 10, diameter 10 mm. 



A second species of Solariella is found commonly at various 

 localities in the Yorktown formation in Virginia and which I have 

 identified with Tuomey and Holmes, Trochus gemma. I have fig- 

 ured a specimen from Grove Wharf on Plate 5, fig's 7, 8, 9. Dall 

 in his Tertiary Geology of Florida units with Tourney and Holmes 

 species the recent Liotia tricarinata Stearns, under the name or 

 L. gemma. L. tricarinata is also a Miocene shell. I have speci- 

 mens from Wilmington, Magnolia, Neuse river, N. C. This 

 last-mentioned species is typically much smaller, generally with a 

 smooth base or at least with only faint revolving lines and lastly 

 with a strong carina bordering the suture. Solariella shakleforden- 

 sis may be distinguished from 6". gemma in having only two strong- 

 ly carinated, ribs more numerous, smaller, plain, revolving lines. 



St Mary' s formation (?); Shakleford, Va. 



Teinostoma (Solariorbis) variabilis, n. sp., Plate 5, Fig's 1-4 



Shell small, solid, rather depressed, but with a slightly point- 

 ed spire ; umbilicated ; whorls 4, enlarging uniformly ; periphery 

 of last whorl, slightly angulated ; suture impressed ; sculpture 

 variable, consisting of simple riblets, crossed by oblique, spi- 

 ral striae ; on the earlier whorls, these riblets are most pro- 

 nounced, becoming gradually obsolete and wave-like on the later; 

 spiral striae persistent ; in some cases the riblets may also con- 

 tinue over a larger portion of the later whorls than usual ; base of 

 shell strongly sculptured, the riblets being here persistent ; in old 

 shells a gerontic stage is introduced, corning after a resting stage 

 and this is characterized by an entire lack of sculpture ; aperture 

 rounded or slightly oblique, and with the edge bordering the um- 

 bilicus thickened ; umbilicus deep, not bordered by a ridge or 

 carina. 



Greater diameter 2, height 1 mm. 



This species is characterized by its variability. From T. un- 



