GASTEROPODA OF THE LOWER GREEN MARLS. 1 35 



of the above with Mr. Gabb's description, however, will show considerable 

 difference between them, owing to the fact that he included two entirely 

 different shells under his specific name, and drew his characters partly from 

 each. The two shells, however, belong to entirely distinct families. He 

 does not appear to have noticed the transverse furrows of the upper part 

 of the volutions of the Mullica Hill shells, unless he included them in his 

 "revolving and longitudinal, depressed lines, producing a cancellated ap- 

 pearance," which is not probable. This shell is readily distinguished from 

 the Timber Creek species, which is described in this volume under the name 

 Pleurotrema solariformis by the more depressed spire, absence of lateral 

 sloping face to the volutions, and by the form and size of the umbilicus. 

 Dr. Morton's Cirrus crotaloides, Synopsis p. 49, PI. xix. Fig. 5, is much more 

 nearly related to it; but from specimens of that species from Alabarpia, it 

 differs remarkably on the basal surface, that one having a broad spreading 

 or open surface below. 



Formation and locality: In marls of the Lower Beds at Mullica Hill, 

 and at Crosswicks Creek, near New Egypt, New Jersey. I have also seen 

 examples of it from Prairie Bluff, Alabama, and Mr. Gabb also recognized 

 it from that place. 



ONUSTID^. 



Genus XENOPHORA Fischer. 



Xenophora leprosa. 



Plate XVII, Figs. 16-19. 



Trochus leprosus Morton: Synop. Org. Rem. Cret., p. 46, PI. xv, Fig. 6. 



Phorus leprosus (Mort.) Gabb: Synopsis, p. 85; Meek, Check List Cret. and Jur. 



Foss., p. 18. 

 Onustus leprosus (Mort.) D'Orb., Prod, de Paldont., vol. 4, p. 232; Meek, Geol. N. 



J., Newark, 1868, p. 728. 



Shell small or below a medium size, trochiform, 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 



