CRETACEOUS FOSSILS. 275 



PUcherii and vesicularis. At the same time the beaks will distinguish them between 

 themselves. 



G, mucronata occurs abundantly among the Mexican fossils. 



EXOGYRA, Say. 

 E. PLICATA, Lam., sp. 



PL 36, Fig. 19, 19 a. 



(Gryphoea 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, Roem. ; Kreid., p. 48.) 



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



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



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



(E. Boiissingaultii, d'Orb. ; Foss. 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. Fr., Vol. 3, p. 702, pi. 468.) 



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



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



(E. Texana, Roem. ; Kreid". Tex., p. 69, 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 

 il Is on these alone that the above long list of names has been proposed. 



OSTREA, Linn. 



O. SP. INDEX. 



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. 



