574 Systematic I'm, koxtology 



Gryphwa vesicularis White, 1SS4, 4th Ann. Rept. U. S. Geol. Survey, p. 303, 



pi. xlviii, figs. 1-5. 

 Gryphwa vesicularis Whitfield, 1S85, Mon. U. S. Geol. Survey, vol. ix, p. 36, 



pi. iii, figs. 15, 16; pi. iv, figs. 1-3; pi. v. 

 Gryphwa vesicularis Notling, 1S97, Mem. Geol. Survey India, Pal., ser. xvi, 



vol. i, p. 39, pi. x, figs. 1, 2. 

 Gryphwa vesicularis Imkeller, 1901, Pal., vol. xlviii, p. 40, pi. ii, figs. 2-4; 



pi. iii, fig. 7-9., 

 Gryphwa vesicularis Hill, 1901, 21st Ann. Rep. U. S. Geol. Survey, pt. vii, pi. 



xlvii, fig. 2. 

 Ostrea (Pycnodonte) vesicularis, Choffat, 1902, Faun. Cret. Portugal, vol. i, 



ser. iii, p. 103, pi. ii, fig. 18. 

 Gryphwa vesicularis Wanner, 1902, Pal., vol. xxx (2), p. 119, pi. xvii, figs. 



10-12. 

 Gryphwa vesicularis Taff, 1902, 22d Ann. Rept. U. S. Geol. Survey, pt. iii, 



pi. 1, figs. 1-3; pi. 11, figs. 1, la; pi. Iii, figs. 1, la. 

 Gryphwa vesicularis Hill and Vaughan, 1902, U. S. Geol. Survey, Geol. Atlas, 



Austin folio, fig. 51. 

 Pycnodonte vesicularis Douville, 1904, Mission Sci. en Perse par J. de Mor- 

 gan, vol. iii, pt. 4, Pal., p. 278, pi. xxxvi, fig. 23. 

 Gryphwa convexa Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 11. 

 Gryphwa mutabilis Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 11. 

 Gryphwa vesicularis Btise, 1906, Bol. Ins. Geol. Mexico, No. 24, p. 49, pi. iv, 



figs. 1-3; pi. vii, fig. 2; pi. ix, fig. 4; pi. xii, fig. 6. 

 Gryphwa vesicularis Veatch, 1906, Prof. Paper U. S. Geol. Survey, No. 46, 



pi. x, figs. l-2a. 

 Ostrea (Gryphwa) vesicularis Boule and Thevenin, 1906, Ann. Paleont, vol. 



i, p. 49 (7), pi. ii, fig. 3. 

 Gryphwa convexa Weller, 1907, Geol. Survey of New Jersey, Pal., vol. iv, p. 



451, pi. xlv, figs. 1, 2. 

 Gryphwa mutabilis Weller, 1907, Ibidem, p. 452, pi. xlvi, fig. 1. 

 Gryphwa dissimilaris Weller, 1907, Ibidem, p. 453, pi. xlvi, figs. 2, 3. 

 Ostrea vesicularis Woods, 1913, Palaeont. Soc, London, Mon. Cret. Lamelli- 



branchia, England, vol. ii, pt. 9, p. 360, pi. Iv, figs. 4-9; text figures 143- 



182. 



Description. — Shell strongly inequivalve, subequilateral, as a rule, sub- 

 circular to semi-circular in outline, often more or less auriculate pos- 

 teriorly; thin to ponderous; umbones central or anterior, orthogyrate, 

 that of the left valve often strongly inflated and turned inward ; left valve 

 convex, often conspicuously so, attached in the umbonal region ; right valve 

 usually a little smaller than the left, flattened or concave; incremental 

 sculpture well defined in both valves, the component layers so obvious in 

 the ponderous individuals that they have the appearance of having slipped 



