1297 



Miocene of Alum Bluff, Calhoun County, Florida, Ball and Burns ; of Jack- 

 son Bluff and other localities nine to sixteen miles southwest of Tallahassee, 

 Vaughan; and between 2236 and 2650 feet in the artesian well at Galveston, 

 Texas, Texas Geological Survey. 



Shell elongate-ovate, subcompressed, produced distally, inequilateral beaks 

 low, prosogyrate, closely concentrically sculptured ; lunule impressed, finely 

 striated, cordate in the young, lanceolate in the full-grown ; escutcheon large, 

 striated, defined by a carina ; sculpture of the disk foliate in front and behind, 

 the middle portion with (normally) numerous thick, depressed, recurved con- 

 centric ribs which conceal the interspaces; exceptionally these ribs may be 

 separated or coalescent, but it is rare that the interspaces are not indicated by 

 sulci ; these are crossed by shallow radial grooves, which, when the interspaces 

 are visible, also cross them ; anteriorly the ribs are convex ventrally, but be- 

 hind the middle of the shell they show a moderate dorsal convexity, giving a 

 flexuous aspect to the shell ; distally the ribs are compressed and elevated, but 

 the foliations are rarely preserved ; internally the hinge is delicate but normal, 

 the teeth entire, the anterior and basal margins crenulate, the adductor scars 

 subequal, the pallial sinus very small but sharply angular. Length 45, height 

 32, diameter 18 mm. 



The figure of the young shell of C. Burnsii was by an accidental transposi- 

 tion referred to this species in the explanation of plate xlii. This is the largest 

 of the Lirophora group in the Florida Tertiary and runs the gamut of variation, 

 like the others. It is more like the Panama Oligocene species than any of the 

 others, but that is smaller, less foliaceous, and relatively more plump and ovate. 



Chione (Lirophora) xesta n. sp. 

 PLATE 55, FIGURE 18. 



Miocene of Alum Bluff, Calhoun County, Florida ; Burns and Dall. 



Shell small, rounded-trigonal, with low, usually sparsely sculptured beaks, 

 a striated cordate lunule, and feebly defined striated escutcheon; sculpture in 

 general resembling that of the other species, but with the ribs high and sharp, 

 or only slightly thickened, clear across the disk, though more elevated distally ; 

 the radial striation appears on the ventral side of the ribs, is not emphatic, and 

 does not cross the interspaces, which are concentrically striated; there are 

 about twenty ribs ; interior as in the C. ulocyma, the base evenly arcuate and 

 not flexuous. Length 30, height 25, diameter 16 mm. 



This species recalls the Vicksburgian C. victoria, which has a smaller 

 lunule, larger pallial sinus, and denser and more elevated concentric lamellation. 



