404 Systematic Paleontology 



"Shell large 1'or the genus, attaining fully an inch in length; very 

 globose, the diameter being nearly as great as the height, at least equalling 

 seven-eighths of the height. Spire low and rounded, and the base only 

 slightly more pointed. Volutions between three and four in number, the 

 outer half of the last one more abruptly deflected downward at the suture 

 than the preceding ones, but again elevated near the aperture. Aper- 

 ture narrow, pointed above and widest below and rounded; the length 

 equal to about four- fifths of the entire length of the shell; columellar mar- 

 gin thickened and marked by horizontal ridges on the upper two-thirds 

 of its length, and by two very strong, ridge-like teeth or plications below 

 the middle, the upper of which is the stronger. Base and outer lip slightly 

 thickened. Surface of the shell, as shown on the cast, marked by fine spiral 

 lines, and by transverse lines of growth. Of the spiral lines, about thirty 

 may be counted on the outer half of the body whorl of the larger indi- 

 vidual, those near the base being coarser than those above, but gradually 

 becoming fainter in strength. On one of Dr. Morton's types the transverse 

 lines are regular and but little less strongly marked than the spiral lines, 

 so that the surface under a glass looks to be cut up into small nearly equal 

 solid nodes."— Whitfield, 1885. 



The species is represented within the area under discussion merely by 

 water-worn casts which have, however, preserved enough of the diagnostic 

 features to make their determination certain. 



Avellana bullata (Morton) is much larger and more globose than any 

 of the co-existent members of the genus. 



Occurrence. — Matawan Formation. Old water-filled marl pit on east 

 bank of cove near Post 236, and opposite Post 201, Chesapeake and Dela- 

 ware Canal, Delaware. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences. 



Outside Distribution. — Matawan Formation. Merehantville clay marl, 

 New Jersey. Monmouth Formation. ? Navesink marl, New Jersey. 



