MOLLUSCA. 691 



1892. Xenophora leprosa Whitf., Pal. N. ]., vol. 2 (Monog. U. 



S. G. S., vol. 18), p. 135, pi. 17, figs. 16-19. 

 1905. Xenophora leprosa Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. 21. 



Description. "Shell small or below a medium size, trochi- 

 f orm, or broad conical ; the spire having an apical angle of less 

 than 90 ; base flat or concave, usually more or less depressed 

 in the center, with the margin of the volution more or less 

 rounded, and in old individuals sometimes distinctly rounded; 

 casts showing a small umbilical perforation, but the axis prob- 

 ably solid in the shell ; volutions probably seven or eight, but in 

 the casts the upper ones are usually absent and seldom show more 

 than four or four and a half; one small specimen retaining the 

 upper whorls, to the number of four and a half, measures omy 

 five-eighths of an inch in diameter. This one, if continued below 

 to the size of the larger one figured, would possess at least eight 

 volutions ; whorls obliquely flattened on their surfaces in the 

 direction of the spire, with only a small portion of their edges 

 rounded or vertical, and the surface deeply and abundantly 

 scarred by the cicatrices of foreign substances which have been 

 attached to the surface of the shell during life; aperture com- 

 pressed, transversely ovate or trapezoidal, and the outer margin 

 much prolonged." (Whitfield.) 



The dimensions of an internal cast are : height, 28 mm. ; max- 

 imum diameter, 44.5 mm. 



Remarks. This species usually occurs in a more or less frag- 

 mentary condition, and in New Jersey it appears to be character- 

 istic of the Navesink marl. The only species with which it can 

 be confused is Hndoptygma umbilicata, but that is a much smaller 

 shell restricted to the Merchantville clay-marl, and is furnished 

 with an internal revolving ridge upon the lower side of the volu- 

 tion, which can always be recognized as a distinct groove in the 

 casts. 



Formation and locality. Navesink marl, Atlantic Highlands 

 (108), Crawfords Corner (i26 7 ), Crosswicks Creek (195), near 

 Jacobstown (150). 



Geographic distribution. New Jersey, Alabama. 



