NO. 2169. 2I0LLVSK.^ OF CTIOCTAWHATCHEE MARL— MANSFIELD. 603 



Twenty genera of pelecypods and two of gastropods are listed from 

 Redbay. On the other hand in the upper bed at Alum Bluff, there 

 are 32 genera of gastropods and 27 of pelecypods listed by Doctor 

 Dall.i 



On account of the small collections and the unidentiiiable 

 character of some specimens, it is not possible to determine the exact 

 synchronism of the famia with that of the upper bed at Alum Bluff, 

 however, the species present indicate that the beds represent nearly 

 the same if not precisely the same horizon. 



The writer wishes to express his thanks to Dr. William H. Dall, of 

 the United States Geological Survey; Dr. Paul Bartsch, of the United 

 States National Museum, and Dr. T. Wayland Vaughan, of the United 

 States Geological Survey, for suggestions kindly offered in the prepara- 

 tion of this paper. 



ARCA (SCAPHARCA) STAMINEA Say. new subspecies RUBISINIANA. 



Plato 113, figs. 1, .3. 



Shell of moderate size, rhombic and inflated; beak prominent, 

 slightly prosogyrate, and situated near anterior third of length of 

 the valve. There are 32 transverse nodulose radiating ribs, which 

 are a httle narrower over the middle of the disk than intervening 

 spaces. Those on the posterior angle and anterior arch are a httle 

 wider. The two radials at the angle on the posterior side and one 

 on the anterior are divided by an incised hne basally for about haK 

 their length. The nodules are quite evenly spread over the disk, 

 except on the posterior side, where they are replaced by nearly square 

 crenulated ribs. In front, the disk is rounded; posteriorly, it is 

 nearly vertically truncated, forming a somewhat extended edge. 

 Anterior margin rounded; basal margin nearly straight; shghtly 

 oblique to hinge line and meeting the posterior margin in a short 

 rounded line. Cardinal area triangular, flattened beneath the beak, 

 and sulcated by four angled impressed Hues. Hinge hne, short, di- 

 rect except at extremities, where it is slightly curved downward. 

 There are 12 anterior and 26 posterior oblique mesially crowded 

 teetli. The inner margin of the valve is fluted; the interior radically 

 striated. 



Tyi)e (Cat. No. 166911, U.S.N.M.).— This measures— length, 36 



i^n.; height,- 31 mm.; diameter (double), 35 mm. 



^ ive-locality. — ^Miocene of Florida, bluff on John Anderson's farm, 



1 miluioy^h of Redbay, Walton County, Florida. George C. Matson, 



collecto. 



D%icu8ifyon. — Other poorly preserved specimens from same locahty 

 are lajger, one measm-ing : length, 40 mm.; height, 40.5 mm.; diame- 



' Trans. Wagner Free Inst. Sci., vol. 3, pt. C, pp. 1596-8. 



