,;6 Pai.akontographica Amekicana 56 



Occur renci. — Pliocene of the Waccamaw beds of South Carolina; and of the Caloos- 

 ahatchie, Shell Creek, Alligator Creek, and Myakka River, Florida. — Dall. Pliocene of 

 Shell Creek, Florida.— C. U. Museum. 



Area catasarca Dall 



Plate XIII, Figure 6 



Scapharca {Anadara)catasarca Dall, Wagner Free Inst. Sci.. Tran.s., vol. 3, pt. 4, p. 654, pi. 32, 

 fig. 20, 1898. 



"Shell elongate, solid, subrhomboidal, with very anterior, high, prosocoelous beaks; 

 right valve with twenty-three strong, narrow, rounded ribs, separated by wider, very 

 deep channelled interspaces; concentric sculpture of incremental lines, which are slightly 

 elevated at regular intervals, and cause over much of the valve the tops of the ribs to 

 appear obscurely nodulous; the ribs on the anterior end, though simple in the young, 

 are sharply mesially sulcate in the adult, those on the posterior dorsal slope lower and 

 more rude than those on the body of the shell ; the hinge-line is straight, the cardinal 

 area differs from that of A . rustica only by having but a single transverse groove anter- 

 iorly between the beaks; both valves are similarly sculptured, but no adult left valve 

 was collected; the hinge-line is straight and shorter than the shell; there are about fif- 

 teen anterior and four times as many similar vertical posterior teeth, the proximal ends 

 of the series slightly overlapping ; the hinge-line in the specimen figured is forty-six mil- 

 limeters long, the vertical of the beak falls at 8.5 millimeters from the anterior end; in- 

 ner matgins thickened, with short flutings. Lon. 55, alt. 36, diam. 45 mm. 



"This fine species appears to be rare, and was found only at Alligator Creek * * *. 

 The young has much the outline of A. auriculata, but is not markedly auriculate. It is 

 proportionately shorter than the adult. The species belongs to the same subordinate 

 group as A. rustica, as is shown by the minor characters. 



"A single broken valve, probably of this species, is among the material from Shell 

 Creek."— Z?a//, 1898. 



Occurrence . — Pliocene marl of Alligator and Shell Creeks, Florida. — Dall. 



Section Cuneai'ca Dal), 1898 



"Group of A. iucoiigrua Say. ( Ciiiieatra Dall.) 



"Thin, trigonal, inflated, with erect beaks; the cardinal area short, amphidetic, 

 equilateral, set off by deep grooves from the rest of the sculpture, smooth or transversely 

 striated, without furrows; hinge-teeth divisible into two series, smaller proximally, larger 

 and more oblique distally, often more or less A-shaped; the right valve smaller; sculp- 

 ture of the two valves obviously discrepant; the epidermis smooth or not pilose." — Dall. 



Area initiator Dall 



Plate XIII, Figures 7, S, 9 



Scapliaica (Cniicarca) iniliator l^jM, Wagner Free Inst. Sci., Trans., vol. 3, pt. 4. p. 634, pi. 32, 

 fig. II, 1S9S. 



