482 CRETACEOUS PALEONTOLOGY. 



1834. Pecten quinqwecostatus Mort., Synop. Org. Rem. Cret. 



Gr. U. S., p. 57, pi. 19, fig. I. 

 1838. Pec ten quinqwecostatus Bronn, Lethaea Geog., Zweiter 



Band, pp. 678-680, taf. 30, fig. 17. 



1849. P^cten qimdrico status Roem., Texas, p. 398. 



1850. Janira mortonii d'Orb., Prod. Paleon. Strat., vol. 2, p. 



253- 

 1852. Pecten qwadricostatws Roem., Kreide von Texas, p. 64, 

 1852. Pecten quadricostatu.s var. Roem., Kreide von Texas, p. 



64, pi. 8, figs. 4 a-c. 

 1854. Pecten quadrico status Shum., Marcy's Expl. Red River 



La., p. 178, pi. 2, figs. 2 a-b, pi. 3, fig. 6. 

 1 861. Neithea mortonii Gabb, Proc. Acad. Nat. Sci. PhiL 



(1861), p. 365. 

 1 861. Ncitlhca mortonii Gabb, Synop. Moll. Cret. Form., p. 



188 (132). 

 1864. Neithea mortoni Meek, Check List Inv. Eoss. N. A.,. 



Cret. and Jur., p. 7. 

 1868. Neithea mortoni Con., Cook's Geol. N. J., p. 725. 

 1870. Pecten quadricostatuis Credner, Zeitsch. Deutsch. GeoL 



Ges., Bd. 22, p. 232. 

 1886. Neithea qu/inquecostata Whitf., Pal. N. J., vol. r 



(Monog. U. S. G. S., vol. 9), p. 56, pi. 8, figs. 12-14. 



Description. — "Shell broadly ovate exclusive oi the auricula- 

 tions, and plano-convex to concavo-convex in profile, right valve 

 strongly convex, with a sharp, arching, and incurved beak ex- 

 tending beyond and partially overarching the hinge-line; hinge- 

 line straight or nearly so, slightly declining on the anterior side;: 

 nearly two-thirds as long as the entire width oi the shell ; auricu- 

 lations moderate in size, the anterior one the smallest and con- 

 stricted below where it joins the body O'f the shell, forming a. 

 slight byssal notch; posterior side triangular, longest at the 

 hinge-line and receding below. Sides of the valve where it joins 

 the auriculations strongly incurved laterally, so as to> cause the 

 sides to overhang. Valve marked by six strong, rounded, prin- 

 cipal radiating co-stse, with from two to four smaller ones be- 



