MOLLUSCA. 451 



Gryphaea convexa (Say). 

 Plate XLV., Figs. 1-2. 



1820. Ostrea convexa Say, Am. Jour. Sci., ist ser., vol. 2, p. 42. 



1828. Gryphcea convexa Mort., Jour. Acad. Nat. Sci. Phil., ist 



ser., vol. 6, p. 79, pi. 4, figs. 1-2. 



1829. Gryphcea convexa Mort., Jour. Acad. Nat. Sci. Phil., ist 



ser., vol. 6, p. 121. 



1830. Gryphcea convexa Mort., Am. Jour. Sci. ist ser., vol. 17, 



p. 283. 

 1834. Gryphcea convexa Mort., Synop. Org. Rem. Cret. Gr. U. 



S., p. 53, pi. 4, %s. 1-2. 



1840. Gryphcea convexa Troost, 5th Geol. Rep. Term., p. 46. 

 1868. Pycnodonta vesicularis Cook, Geol. N. J., p. 374, figs. 

 1884. Gryphcea vesicularis White (in part), 4th Ann. Rep. U. 



S. G. S., p. 303, pi. 48, figs. 1-5. 

 1886. Gryphcea vesicularis Whitf. (in part), Pal. N. J., vol. i 



(Monog. U. S. G. S., vol. 9), p. 36, pi. 3, fig. 15, pi. 4, 



figs. 1-2. 

 1902. Gryphcea vesicularis Hill and Vaughan, U. S. G. S., Geol. 



Atlas, Austin Folio, fig. 51. 

 1905. Gryphcea convexa Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. II. 



Description. Shell variable in outline, large and robust, ob- 

 lique, very thick, the surface more or less rugose, the beak in 

 front of middle of the shell. Lower valve strongly convex, more 

 or less auriculate posteriorly, the auriculation separated from the 

 body of the shell by a conspicuous sinus which extends from 

 behind the beak obliquely backward to the posterior margin of 

 the shell, the cardinal side of the auriculation usually flattened 

 and somewhat elevated; the body of the shell most strongly 

 elevated along a line which extends obliquely backward from 

 the beak to the basal margin, this prominence being more or less 

 rounded or in some cases almost subangular ; the posterior slope 

 of the shell surface to the sinus limiting the auriculation is usu- 

 ally more abrupt than the anterior slope. The scar of attachment 



