GASTEROPODA OF THE LOWER GREEN MARLS. 163 



f 



Gabb, from wliich it is very difficult to distinguish it. The specimens of 

 that species used by Mr. Gabb are, however, a Httle more slender or pointed 

 in the lower part. 



Formation and locality: In the Lower Green Marls at Crosswicks, New 

 Jersey. Collection Acad. Nat. Sci., Phila. 



Genus AVELLANA D'Orb. 



AVELLANA BULLATA. 



Plate XX, Figs. 1-4. 



TomateUa ? bullata Morton : Synop. Org. Rem. Cret. , p. 48, PL v, Fig. 3. 

 SoUdula bullata (Morton) Gabb : Synopsis, p. 81; Meek, Check List Cret. and Jur. 

 Foss., p. 17; Geol. N. J., Newark, 1868, p. 728. 



Shell large for the genus, attaining fully an inch in length; very 

 globose, the diameter being nearly as great as the height, at leaot equal- 

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

 only slightly more pointed. Volutions between three and four in num- 

 ber, the outer half of the last one more abruptly deflected downward at 

 the suture than the preceding ones, but again elevated near the aperture. 

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

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

 margin thickened and marked by horizontal ridges on the upper two- 

 thirds of its length, and by two very strong, ridge-like teeth or plica- 

 tions 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 individual, these 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. 



The species is remarkable for its large size and globose form, and also 

 among the New Jersey forms for the strong columellar folds or plaits, the 

 upper of which is much the largest. The horizontal line-like gi-anules of 



