14 



Palaeontographica Americana 14 



The variety figured and described by Professor Harris (Bull. Am. Pal., vol. 2, no. 9, 

 p. 47, pi. 8, figs. I, la, 1897), has a more pointed posterior basal angle and rougher pos- 

 terior ribs than the type. It is from the Sabine Eocene of Gregg' s Landing, Alabama. 

 Naviatla aspersa Conrad, Wailes, Agr. and Geol. Mississippi, p. 289, pi. 14, fig. 5, 1854; 

 Navicula aspcra Conrad, Acad. Nat. Sci. Phila., Proc. for 1855, p. 258, 1855; not Area 

 aspera Phil., Moll. Sicil., 1836 {Me Dall) has been listed in synonymies as the young of 

 A. cucullotdes, but the specimen in the Philadelphia Academy is Acar reticulata . 



Dimensions. — Lon.-fi8,-4o; alt. + 7, -39 ; semidiam. 19 mm. 



Occurrence. — Upper Eocene (Jacksonian) near Claiborne, Alabama; Jackson, Missis- 

 sippi; Cleveland County, Arkansas; and in the Lower Oligocene at Vicksburg, Missis- 

 sippi. — Dall. Sabine Eocene of Gregg's Landing, Alabama and Pendleton, Texas, and 

 Jackson Eocene of Jackson, Mississippi, of Montgomery, Grandview Bluff, Gibson's 

 Landing and Bunker Hill Landing, Louisiana and of Texas, — C. U. Museum. 



Area mississippiensis Conrad 

 Plate in. Figures i, 2, 3, 4 



Byssoarca tnississippiensis Conrad, Acad. Nat. Sci., Phila., Proc. for 1847, p. 295; Joiirn., 2d. ser., 



vol. I, p. 125, pi 13, fig. 32, 1848. 

 t^ot Area titississtppicnsis Conrad, Acad. Nat. Sci. Phila., Journ., 2d. ser. . vol. i, p. 125, pi. 13, 



figs. II, 15, 184S. 

 Navicula mississippiensis Conrad, Acad, Nat. Sci. Phila., Proc. for 1854, p. 29. 

 Cucullo'arca mississippiensis Conrad, Am. Journ. Conch., vol. i, p. 11, 1865. 

 Barbatia mississippiensis Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt. 4, p. 625, 1898. 



"Trapezoidal, with nimierous closely arranged radiating lines, crenulated by fine 

 concentric lines, the crenulation most distinct anteriorly, where the radii are largest; an- 

 terior end truncated or a little convex, direct: posterior margin obliquely truncated 

 above; basal margin widely and profoundly arched; hinge line long, linear, minutely 

 crenulated, expanded towards the extremities, and with prominent teeth ; cardinal area 

 with fine, very closely-arranged lines, angulated under the apex. Length i 6-10. 



"Differs from the preceding \B. limd\ in having a longer hinge, finer radii, etc., and 

 is a much smaller species and more abundant." — Conrad, 1848. 



This species is much like A. tnarylandica. It is separated from A. cuculloides by its 

 even ribbing and lack of the sharp timbonal ridge which characterizes that species. 



Dimensions. — (Small valve). Ion. -(-9,-20; alt, 4-2.5,-16; semidiam. 6 mm. 



Occurrence. — Vicksburg Oligocene of Vicksburg, Mississippi.— C. U. Musciun. 



Area marylandica Conrad 

 Plate III, Figures 5, 6, 7 



Byssoarca marylandica Conrad, Fos. Med. Tert., \i. 54, pi. 29, fig. i, 1840. 



Navicula marylandica Conrad, Acad. Nat. Sci. Phila., Proc. for 1854, p. 29. 



Barbatia {Byssoarca) matylandica Conrad, Acad. Nat. Sci. Phila., Proc. for 1862, p. 580, 1863. 



Area marylandica Heilprin, Acad. Nat. Sci. Phila., Proc. for 1880, p. 21. 



Barbatia (Calloarca) marylandica Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt. 4, p. 623, 1898. 



Area (Barbatia) marylandica Glenn, Maryland Geol. Rurv., Miocene, p. 392, pi. 106, fig. 7, 1904. 



