596 SYSTEMATIC PALEONTOLOGY 



P. simplicius Conrad has been confused in the synonymies with P. con- 

 radi Whitfield, a slightly larger shell which is characterized by the develop- 

 ment of sharp, elevated, concentric lamellae, approximately fifteen in 

 number. The typical forms of the two species are conspicuously distinct 

 but some of the peripheral members are difficult to separate. 



Occurrence. M ATA WAN FORMATION. Ulmstead Point, Anne Arundel 

 County. MONMOUTH FORMATION. Brightseat, Brooks estate near Seat 

 Pleasant, Friendly, 1 mile west of Friendly, and McNeys Corners, Prince 

 George's County. 



Collections. Maryland Geological Survey, New Jersey Geological Sur- 

 vey, U. S. National Museum. 



Outside Distribution. Monmouth Formation. Eed Bank sand and 

 Tinton beds, New Jersey. Black Creek Formation. North and South 

 Carolina. Peedee Sand. North and South Carolina. Eutaw Formation 

 (Tombigbee sand member). Exogyra ponderosa zone, Mortoniceras sub- 

 zone, Georgia. Ripley Formation. Exogyra ponderosa zone, Union 

 Springs, Alabama. Exogyra costata zone, Georgia; Eufaula, Alabama. 

 Extreme top of zone, Pataula Creek, Georgia ; Chattahoochee River, Ala- 

 bama; Lowndes County, Mississippi. 



PECTEN QUINQUECOSTATUS Sowerby 

 Plate XXXIV, Fig. 10 



Pecten quinqueco status Sowerby, 1814, Min. Conch., vol. i, p. 122, pi. Ivi, 



figs. 4-8. 



Pecten versicostatus Lamarck, 1819, Anim. sans Vert., vol. vi, p. 181. 

 Pecten quinquecostatus Brongniart, 1822, Geol. des Env. Paris, pi. iv, fig. 1. 

 Pecten quinquecostatus Nilsson, 1827, Petrif. Suecana, p. 19, tab. ix, fig. 8; 



tab. x, fig. 7. 

 Pecten quinquecostatus Morton, 1830, Am. Jour. Sci., 1st ser., vol. xvii, p. 



285; vol. xviii, pi. iii, fig. 5. 



Pecten versicostatus Deshayes, 1832, Enc. Meth., t. 3, p. 727. 

 Pecten quinquecostatus Morton, 1834, Syn. Org. Rem. Cret. Group U. S., p. 



57, pi. xix, fig. 1. 



Pecten quinquecostatus Goldfuss, 1836, Petrif. Germ., t. 93, fig. 1. 

 Pecten quinquecostatus Bronn, 1838, Lethsea Geogn., Bd. ii, pp. 678-680, taf. 



xxx, fig. 17. 

 Janira quinquecostata d'Orbigny, 1846, Paleont. Franc. Terr. Cret, vol. iii, 



p. 632, pi. ccccxliv, figs. 1-5. 



