MOLLUSCA. 717 



growth, and the younger ones have the external markings of 

 the shell more strongly impressed, as if the shell were thinner 

 during its earlier growth, becoming thickened internally later so 

 as to abscure the external markings. Entirely similar casts 

 occur at Prairie Bluff, Alabama, and elsewhere in the south. 



Whitfield has referred his species R. nobilis to the "Upper," 

 or Manasquan marl, with a query, but there is no data with the 

 specimen, and from its lithologic characters it seems to be more 

 properly referred to the Navesink, the horizon to which the 

 species seems to be restricted. 



Formation and locality. Navesink marl, near Crawfords 

 Corner (i26 7 ), Mullica Hill (169). 



Geographic distribution. New Jersey, Alabama, Mississippi. 



Anchura arenaria (Morton). 

 Plate LXXXIIL, Fig. 5. 



1834. Rostellaria arenarum Mort., Synop. Org. Rem. Cret. Gr. 



U. S,, p. 48, pi. 5, fig- 8. 

 1861. Gladius arenarum Gabb, Synop. Moll. Cret. Form., p. 



no (54). 

 1864. Rostellaria (?) arenarum Meek, Check List Inv. Foss. 



N. A., Cret. and Jur., p. 20. 



1868. Anchura arenarum Con., Cook's Geol. N. J., p. 729. 

 1876. Anchura arenarum Gabb, Proc. Acad. Nat. Sci. Phil. 



(1876), p. 298. 

 1892. Anchura arenaria Whitf., Pal. N. J., vol. 2 (Monog. U. 



S. G. S., vol. 18), p. 112, pi. 14, fig. 10. 

 1905. Anchura arenaria* Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. 22. 



Description,. Shell rather strong and robust, about 50 mm. 

 in length when complete and 24 mm. in width. Volutions prob- 

 ably four and one-half or five in number, strongly rounded, rap- 

 idly decreasing in size upward ; suture strongly marked ; aperture 

 narrow, the lip unknown, the rostrum apparently quite short. 

 Each volution marked by 10 or 12 vertical plications or folds, 



