588 SYSTEMATIC PALEONTOLOGY 



PECTEN AEGILLENSIS Conrad 

 Plate XXXIV, Figs. 3-5 



Pecten argillensis Conrad, 1860, Jour. Acad. Nat. Sci., Phila., 2 ser., vol. 



iv, p. 283. 

 Pecten argillensis Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 7. 

 Camptonectes bellisculptus Conrad, 1869, Am. Jour. Conch., vol. v, p. 99, pi. 



ix, fig. 11. 

 Camptonectes (Amusiumj burlingtonensis Whitfield, 1885, Mon. U. S. Geol. 



Survey, vol. ix, p. 53, pi. viii, figs. 3-7, 9 (not fig. 8) (ex parte) ; not 



Pecten burlingtonensis Gabb, 1860. 



Pecten bellisculptus Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 11. 

 Pecten argillensis Weller, 1907, Geol. Survey of New Jersey, Pal., vol. iv, 



p. 472, pi. xlix, figs. 1-4. 



Description. " Suborbicular, very thin, compressed ; radiated only on 

 the upper part with minute lines ; disk covered with closely arranged, fine 

 lamelliform striae, except on the umbo and adjacent parts where they are 

 distant; posterior margin opposite the ear carinated. (Upper valve.)" 

 Conrad, 1860. 



Type Locality. Owl Creek, Tippah County, Mississippi. 



Shell rather thin and fragile, compressed, subequivalve ; outline, exclu- 

 sive of the auricles, a sector of approximately 90 ; hinge line straight, a 

 little more than half as wide as the shell; auricles broad but rather low; 

 surface ornamentation elaborate but not conspicuous, radial sculpture 

 of finely incised lines, two to four to the millimeter, on the disks of the 

 adults, straight in the medial portion but sweeping in gentle curves 

 toward the lateral margins deeper and a little broader posteriorly than 

 anteriorly; concentric lines thirty to forty in number, over-riding and 

 intercepting the radials, finely and evenly crenulated and in the umbonal 

 region of perfectly preserved adults, minutely moniliform; auricles very 

 unequal, the anterior broader and relatively lower than the posterior; 

 posterior auricle sculptured with approximately fifteen coarse lirations 

 running oblique to the hinge margin, rendered minutely scabrous by the 

 over-riding incrementals ; anterior auricle long and narrow, alate in 

 outline, the striations radiating from the umbonal extremity, sweeping in 

 rather abrupt curves to the dorsal margin; byssal sinus narrow and very 



