44 



CRETACEOUS LAMELLIBRANCHIA. 



Genus — Gkammatodon, Meek and Hayden (I860), 1864. 1 



[' Proc. Acad. Nat. Sci. Philad.,' 1860, p. 419 (list name) ; " Palaeontology of the Upper Missouri," 

 ' Smithsonian Contrib. to Knowledge,' vol. xiv, No. 172, 1864, p. 89, pi. ii, fig. 9.] 



Gkammatodon securis (Leymerie), 1842. Plate VII, figs. 14 a, b, 15 a, b; Plate 



1829. CucuLLiEA, J. Phillips. G-eol. Yorks., pt. 1, p. 186, pi. ii, fig. 16. 

 1842. — securis, A. Leymerie. Mem. Soc. Geol. France, vol. v, p. 6, 



pi. vii, figs. 6, 7. 



1844. Aeca secttbis, A. d'Orbigny. Pal. Franc. Terr. Cret., vol. iii, p. 203, 



pi. cccix, figs. 9, 10. 



1845. — — F. Forbes. Quart. Journ. Geol. Soc, vol. i, p. 246. 

 1850. — — A. d'Orbigny. Prodr. de Pal., vol. ii, p. 80. 



1854. — — J. Morris. Cat. Brit. Foss., ed. 2, p. 185. 



1855. — — G. Cotteau. Moll. Foss. de l'Tonne, p. 87. 



1861. — — P. de Loriol. Anim. Invert. Foss. du Mont Saleve, p. 86, 



pi. x, fig. 8. 

 1866. — — F.J. Pictet and G. Campiche. Foss. Terr. Cret. de Ste. 



Croix (Mater. Pal. Suisse, ser. 4), pt. 3, pp. 443, 469. 

 1875. Cucull^a securis, /. Phillips. Geol. Yorks., pt. 1, ed. 3, p. 323, pi. ii, 



fig. 16. 

 1896. Arca securis, A. Wollemann. Zeitschr. d. deutsch. geol. Gesellsch., 



vol. xlviii, p. 845. 



Measurements : 



Length 21 mm. 



Height 14 



Thickness 12'5 „ 



Affinities. — This form, as was pointed out by de Loriol, is very similar to 

 Grammatodon carinatus (Sowerby) (see p. 45), and I think it is possible that they 

 may prove to be identical, but until more specimens have been obtained I shall 

 regard the two as distinct. In G. securis the area appears to be broader 

 than in G. carinata ; and also on the left valve of the former the ribs are more 

 widely separated than in the latter, and there are small ribs in the interspaces. 

 Gucullsea Schusteri, Roemer, 2 is perhaps an allied form, but I have seen no speci- 

 men of it. 



Remarks. — The specimen figured by d'Orbigny is proportionately longer than 



1 For the synonj'my of this genus see Woods, 'Ann. Mag. Nat. Hist.,' ser. vii, vol. iii (1899), 

 p. 47. To the names there given should be added Beushausenia, Cossmann, ' Rev. crit. Paleozool.' 

 (1897), p. 93. 



2 'Die Verstein des nord-deutsch. Kreidegeb.' (1841), p. 70, pi. ix, fig. 3. 



