360 CRETACEOUS PALEONTOLOGY. 



1829. Terebratula fragilis Mort., Am. Jour. Sci., ist ser., vol. 



17, p. 283; vol. 18, p. 250, pi. 3, fig. 17. 

 1834. Terebratula fragilis Mort., Synop. Org. Rem. Cret. Gr. 



U. S., p. 70, pi. 3, fig. 2. 

 1886. Terebratula Harlani var. fragilis Whitf., Pal. N. J., vol. 



i, (Monog. U. S. G. S., vol. 9), p. 7, pi. i, figs. 15-18. 



Description. The name fragilis was applied by Morton to 

 those specimens of T. harlani which are more conspicuously pli- 

 cated anteriorly than usual. There is no sharp line of demar- 

 cation between the variety and the more typical form of the 

 species, all intermediate variations being met with, and all of 

 them occurring together. It will, perhaps, be a matter of con- 

 venience to recognize this form under a varietal name, and if this 

 is done, Morton's name fragilis takes precedence, although it has 

 no especial significance, the shells being no more fragile than 

 those of the typical T. harlani. 



Genus TEREBRATUUNA d'Orbigny. 



Terebratulina atlantica (Morton). 



Plate XXVIII., Figs. 9-12. 

 1842. Terebratula atlantica. Mort., Jour. Acad. Nat. Sci. Phil., 



ist ser., vol. 8, p. 214. 

 1861. Terebratulina Halliana Gabb, Proc. Acad. Nat. Sci. 



Phil., 1861, p. 19. 

 1861. Terebratulina Halliana Gabb, Synop. Moll. Cret. Form., 



p. 256 (200). 

 1864. Terebratulina Halliana Meek, Check List Inv. Foss N. 



A., Cret. and Jur., p. 5. 

 1868. Terebratula glossa Con., Cook's Geol. N. J., p. 377, 



figure; p. 723. 



1868. Terebratulina- Halliana Con., Cook's Geol. N. J., p. 724. 



1869. Terebratula glossa Con., Am. Jour. Conch., vol. 5, p. 42, 



pi. i, fig. 22. 

 1886. Terebratulina Atlantica Whitf., Pal. N. J., vol. i 



(Monog. U. S. G. S., vol. 9), p. 9, pi. i, figs. 1013. 

 1892. Terebratulina atlantica Hollick, Trans. N. Y. Acad. Sci., 



vol. n, p. 98, pi. i, fig. 8. 



