CRETACEOUS FOSSILS. 275 



Pitcher ii and vesicularis. At the same time the beaks will distinguish thorn between 

 themselves. 



O. mucronala occurs abundantly among the Mexican fossils. 



EXOGYRA, Say. 

 E. plicata, Lain., sp. 



PI. 36, Fig. 19, 19 a. 



(Gryphma plicata, Lam. ; 1819, An. S. Vert., Vol. 6, p. 199.) 



(Exogyra plicata, Goldf. ; Petr. Germ., Vol. 2, p. 37, pi. 87, fig. 5.) 



(E. plicata, Poem. ; Kreid., p. 48.) 



(E. flabellata, Goldf. ; Petr. Germ., Vol. 2, p. 38, pi. 87, fig. 6 (young) ). 



(Ostreaflabellata, d'Orb. ; Pal. Pr., Vol. 3, p. 717, pi. 475.) 



(E. harpa, Goldf. ; Petr. Germ., Vol. 2, p. 38, pi. 87, fig. 7.) 



(Gryphcea harpa, Fbs. ; Quart. Jour. Geol. Soc, 1844, p. 250, pi. 3, fig. 12.) 



(Ostrea Matheroniana, d'Orb ; Pal. Pr., Vol. 3, p. 737, pi. 485.) 



(E. Matheroniana, Con. ; Emory's Rep., p. 154, pi. 8, fig. 11.) 



(E. Boussingaultii, d'Orb. ; Poss. de Col., p. 57, pi. 3, fig. 10 ; pi. 5, fig. 8, 9.) 



(E. Boussingaultii, d'Orb. ; Am. Merid., p. 91, pi. 18, fig. 20.) 



(Ostrea Boussingaultii, d'Orb. ; Pal. Pr., Vol. 3, p. 702, pi. 468.) 



(E. subplicata, Roem. ; Ool. JSTach., tab. 18, fig. 17.) 



(E. spinosa, Math. ; Cat., p. 192, pi. 32, fig. 6, 7.) 



(E. Texana, Roem.; Kreid. Tex., p. 09, pi. 10, fig. 1 a, b, c, d.) 



(E. Texana, Shum. ; Marcy's Rep., Red. R., p. 205, pi. 5, fig. 1, 2.) 



Quite common in Texas and at Arivechi, as well as at all or most of the inter- 

 mediate localities. I cannot believe that, in an oyster, the number or size of the 

 plications, within reasonable limits, can be depended upon as of specific value, and 

 i( "is on these alone that the above long list of names has been proposed. 



OSTREA, Linn. 



O. SP. INDET. 



A small, thin oyster occurs, incrusting many of the larger fossils, and growing 

 in clusters. It is rarely more than an inch or an inch and a quarter long, is closely 

 attached by the whole lower surface, and, where not crowded out of shape, is irregu- 

 larly trigonal, a little oblique, and narrows regularly towards the beaks. 



